diff --git a/swad_assignment.c b/swad_assignment.c
index e0c0fb52..a1a5f387 100644
--- a/swad_assignment.c
+++ b/swad_assignment.c
@@ -742,8 +742,8 @@ static void Asg_GetListAssignments (struct Asg_Assignments *Assignments)
 	   NumAsg++)
         {
          /* Get next assignment code */
-         if ((Assignments->LstAsgCods[NumAsg] = DB_GetNextCode (mysql_res)) < 0)
-            Lay_ShowErrorAndExit ("Error: wrong assignment code.");
+         if ((Assignments->LstAsgCods[NumAsg] = DB_GetNextCode (mysql_res)) <= 0)
+            Lay_WrongAssignmentExit ();
         }
      }
    else
@@ -1033,8 +1033,8 @@ void Asg_ReqRemAssignment (void)
    Assignments.CurrentPage = Pag_GetParamPagNum (Pag_ASSIGNMENTS);
 
    /***** Get assignment code *****/
-   if ((Asg.AsgCod = Asg_GetParamAsgCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of assignment is missing.");
+   if ((Asg.AsgCod = Asg_GetParamAsgCod ()) <= 0)
+      Lay_WrongAssignmentExit ();
 
    /***** Get data of the assignment from database *****/
    Asg_GetDataOfAssignmentByCod (&Asg);
@@ -1070,8 +1070,8 @@ void Asg_RemoveAssignment (void)
    Assignments.CurrentPage = Pag_GetParamPagNum (Pag_ASSIGNMENTS);
 
    /***** Get assignment code *****/
-   if ((Asg.AsgCod = Asg_GetParamAsgCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of assignment is missing.");
+   if ((Asg.AsgCod = Asg_GetParamAsgCod ()) <= 0)
+      Lay_WrongAssignmentExit ();
 
    /***** Get data of the assignment from database *****/
    Asg_GetDataOfAssignmentByCod (&Asg);	// Inside this function, the course is checked to be the current one
@@ -1120,8 +1120,8 @@ void Asg_HideAssignment (void)
    Assignments.CurrentPage = Pag_GetParamPagNum (Pag_ASSIGNMENTS);
 
    /***** Get assignment code *****/
-   if ((Asg.AsgCod = Asg_GetParamAsgCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of assignment is missing.");
+   if ((Asg.AsgCod = Asg_GetParamAsgCod ()) <= 0)
+      Lay_WrongAssignmentExit ();
 
    /***** Get data of the assignment from database *****/
    Asg_GetDataOfAssignmentByCod (&Asg);
@@ -1157,8 +1157,8 @@ void Asg_ShowAssignment (void)
    Assignments.CurrentPage = Pag_GetParamPagNum (Pag_ASSIGNMENTS);
 
    /***** Get assignment code *****/
-   if ((Asg.AsgCod = Asg_GetParamAsgCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of assignment is missing.");
+   if ((Asg.AsgCod = Asg_GetParamAsgCod ()) <= 0)
+      Lay_WrongAssignmentExit ();
 
    /***** Get data of the assignment from database *****/
    Asg_GetDataOfAssignmentByCod (&Asg);
diff --git a/swad_banner.c b/swad_banner.c
index f77fc4b9..2a8c4966 100644
--- a/swad_banner.c
+++ b/swad_banner.c
@@ -324,8 +324,8 @@ static void Ban_GetListBanners (struct Ban_Banners *Banners,
 	 row = mysql_fetch_row (*mysql_res);
 
 	 /* Get banner code (row[0]) */
-	 if ((Ban->BanCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-	    Lay_ShowErrorAndExit ("Wrong code of banner.");
+	 if ((Ban->BanCod = Str_ConvertStrCodToLongCod (row[0])) <= 0)
+	    Lay_WrongBannerExit ();
 
 	 /* Get if banner is hidden (row[1]) */
 	 Ban->Hidden = (row[1][0] == 'Y');
@@ -572,8 +572,8 @@ void Ban_RemoveBanner (void)
    Ban_ResetBanner (&Ban);
 
    /***** Get banner code *****/
-   if ((Ban.BanCod = Ban_GetParamBanCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of banner is missing.");
+   if ((Ban.BanCod = Ban_GetParamBanCod ()) <= 0)
+      Lay_WrongBannerExit ();
 
    /***** Get data of the banner from database *****/
    Ban_GetDataOfBannerByCod (&Ban);
@@ -636,8 +636,8 @@ void Ban_HideBanner (void)
 static void Ban_ShowOrHideBanner (struct Ban_Banner *Ban,bool Hide)
   {
    /***** Get banner code *****/
-   if ((Ban->BanCod = Ban_GetParamBanCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of banner is missing.");
+   if ((Ban->BanCod = Ban_GetParamBanCod ()) <= 0)
+      Lay_WrongBannerExit ();
 
    /***** Get data of the banner from database *****/
    Ban_GetDataOfBannerByCod (Ban);
@@ -723,8 +723,8 @@ static void Ban_RenameBanner (struct Ban_Banner *Ban,
 
    /***** Get parameters from form *****/
    /* Get the code of the banner */
-   if ((Ban->BanCod = Ban_GetParamBanCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of banner is missing.");
+   if ((Ban->BanCod = Ban_GetParamBanCod ()) <= 0)
+      Lay_WrongBannerExit ();
 
    /* Get the new name for the banner */
    Par_GetParToText (ParamName,NewBanName,MaxBytes);
@@ -815,8 +815,8 @@ void Ban_ChangeBannerImg (void)
 
    /***** Get parameters from form *****/
    /* Get the code of the banner */
-   if ((Ban.BanCod = Ban_GetParamBanCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of banner is missing.");
+   if ((Ban.BanCod = Ban_GetParamBanCod ()) <= 0)
+      Lay_WrongBannerExit ();
 
    /* Get the new WWW for the banner */
    Par_GetParToText ("Img",NewImg,Ban_MAX_BYTES_IMAGE);
@@ -866,8 +866,8 @@ void Ban_ChangeBannerWWW (void)
 
    /***** Get parameters from form *****/
    /* Get the code of the banner */
-   if ((Ban.BanCod = Ban_GetParamBanCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of banner is missing.");
+   if ((Ban.BanCod = Ban_GetParamBanCod ()) <= 0)
+      Lay_WrongBannerExit ();
 
    /* Get the new WWW for the banner */
    Par_GetParToText ("WWW",NewWWW,Cns_MAX_BYTES_WWW);
@@ -1155,8 +1155,8 @@ void Ban_ClickOnBanner (void)
    struct Ban_Banner Ban;
 
    /***** Get banner code *****/
-   if ((Ban.BanCod = Ban_GetParamBanCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of banner is missing.");
+   if ((Ban.BanCod = Ban_GetParamBanCod ()) <= 0)
+      Lay_WrongBannerExit ();
 
    /***** Get data of the banner from database *****/
    Ban_GetDataOfBannerByCod (&Ban);
diff --git a/swad_building.c b/swad_building.c
index ee314fcf..a9d6b71c 100644
--- a/swad_building.c
+++ b/swad_building.c
@@ -368,8 +368,8 @@ void Bld_GetListBuildings (struct Bld_Buildings *Buildings,
          row = mysql_fetch_row (mysql_res);
 
          /* Get building code (row[0]) */
-         if ((Building->BldCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-            Lay_ShowErrorAndExit ("Wrong code of building.");
+         if ((Building->BldCod = Str_ConvertStrCodToLongCod (row[0])) <= 0)
+            Lay_WrongBuildingExit ();
 
          /* Get the short name of the building (row[1]) */
          Str_Copy (Building->ShrtName,row[1],sizeof (Building->ShrtName) - 1);
@@ -551,8 +551,8 @@ void Bld_RemoveBuilding (void)
    Bld_EditingBuildingConstructor ();
 
    /***** Get building code *****/
-   if ((Bld_EditingBuilding->BldCod = Bld_GetParamBldCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of building is missing.");
+   if ((Bld_EditingBuilding->BldCod = Bld_GetParamBldCod ()) <= 0)
+      Lay_WrongBuildingExit ();
 
    /***** Get data of the building from database *****/
    Bld_GetDataOfBuildingByCod (Bld_EditingBuilding);
@@ -648,8 +648,8 @@ static void Bld_RenameBuilding (Cns_ShrtOrFullName_t ShrtOrFullName)
 
    /***** Get parameters from form *****/
    /* Get the code of the building */
-   if ((Bld_EditingBuilding->BldCod = Bld_GetParamBldCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of building is missing.");
+   if ((Bld_EditingBuilding->BldCod = Bld_GetParamBldCod ()) <= 0)
+      Lay_WrongBuildingExit ();
 
    /* Get the new name for the building */
    Par_GetParToText (ParamName,NewClaName,MaxBytes);
@@ -741,8 +741,8 @@ void Bld_ChangeBuildingLocation (void)
 
    /***** Get parameters from form *****/
    /* Get the code of the building */
-   if ((Bld_EditingBuilding->BldCod = Bld_GetParamBldCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of building is missing.");
+   if ((Bld_EditingBuilding->BldCod = Bld_GetParamBldCod ()) <= 0)
+      Lay_WrongBuildingExit ();
 
    /* Get the new location for the building */
    Par_GetParToText ("Location",NewLocation,Bld_MAX_BYTES_LOCATION);
@@ -942,7 +942,7 @@ static void Bld_EditingBuildingConstructor (void)
   {
    /***** Pointer must be NULL *****/
    if (Bld_EditingBuilding != NULL)
-      Lay_ShowErrorAndExit ("Error initializing building.");
+      Lay_WrongBuildingExit ();
 
    /***** Allocate memory for building *****/
    if ((Bld_EditingBuilding = malloc (sizeof (*Bld_EditingBuilding))) == NULL)
diff --git a/swad_changelog.h b/swad_changelog.h
index 063ba38b..2d19c007 100644
--- a/swad_changelog.h
+++ b/swad_changelog.h
@@ -600,13 +600,14 @@ TODO: Salvador Romero Cort
 
 TODO: FIX BUG, URGENT! En las fechas como parámetro Dat_WriteParamsIniEndDates(), por ejemplo al cambiar el color de la gráfica de accesos por día y hora, no se respeta la zona horaria.
 */
-#define Log_PLATFORM_VERSION	"SWAD 20.67.1 (2021-04-24)"
+#define Log_PLATFORM_VERSION	"SWAD 20.67.2 (2021-04-25)"
 #define CSS_FILE		"swad20.45.css"
 #define JS_FILE			"swad20.6.2.js"
 /*
 TODO: Rename CENTRE to CENTER in help wiki.
 TODO: Rename ASSESSMENT.Announcements to ASSESSMENT.Calls_for_exams
 
+	Version 20.67.2:  Apr 25, 2021  Code refactoring in error messages. (309482 lines)
 	Version 20.67.1:  Apr 24, 2021  Code refactoring in error messages. (309415 lines)
 	Version 20.67:    Apr 24, 2021  Bug fixing and code optimizations related to user's roles. (309356 lines)
 	Version 20.66.5:  Apr 23, 2021  Including missing head files.
diff --git a/swad_degree.c b/swad_degree.c
index 1b5bd7b4..8dc5662d 100644
--- a/swad_degree.c
+++ b/swad_degree.c
@@ -904,7 +904,7 @@ static void Deg_ListOneDegreeForSeeing (struct Deg_Degree *Deg,unsigned NumDeg)
    /***** Get data of type of degree of this degree *****/
    DegTyp.DegTypCod = Deg->DegTypCod;
    if (!DT_GetDataOfDegreeTypeByCod (&DegTyp))
-      Lay_ShowErrorAndExit ("Code of type of degree not found.");
+      Lay_WrongDegTypExit ();
 
    if (Deg->Status & Deg_STATUS_BIT_PENDING)
      {
diff --git a/swad_degree_type.c b/swad_degree_type.c
index 0bffb4da..89f82eb5 100644
--- a/swad_degree_type.c
+++ b/swad_degree_type.c
@@ -718,8 +718,8 @@ void DT_GetListDegreeTypes (Hie_Lvl_Level_t Scope,DT_Order_t Order)
          row = mysql_fetch_row (mysql_res);
 
          /* Get degree type code (row[0]) */
-         if ((Gbl.DegTypes.Lst[NumTyp].DegTypCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-            Lay_ShowErrorAndExit ("Wrong code of type of degree.");
+         if ((Gbl.DegTypes.Lst[NumTyp].DegTypCod = Str_ConvertStrCodToLongCod (row[0])) <= 0)
+            Lay_WrongDegTypExit ();
 
          /* Get degree type name (row[1]) */
          Str_Copy (Gbl.DegTypes.Lst[NumTyp].DegTypName,row[1],
@@ -804,7 +804,7 @@ void DT_RemoveDegreeType (void)
 
    /***** Get data of the degree type from database *****/
    if (!DT_GetDataOfDegreeTypeByCod (DT_EditingDegTyp))
-      Lay_ShowErrorAndExit ("Code of type of degree not found.");
+      Lay_WrongDegTypExit ();
 
    /***** Check if this degree type has degrees *****/
    if (DT_EditingDegTyp->NumDegs)	// Degree type has degrees => don't remove
@@ -842,7 +842,7 @@ long DT_GetAndCheckParamOtherDegTypCod (long MinCodAllowed)
 
    /***** Get and check parameter with code of degree type *****/
    if ((DegTypCod = Par_GetParToLong ("OthDegTypCod")) < MinCodAllowed)
-      Lay_ShowErrorAndExit ("Code of degree type is missing or invalid.");
+      Lay_WrongDegTypExit ();
 
    return DegTypCod;
   }
@@ -960,7 +960,7 @@ void DT_RenameDegreeType (void)
 
    /***** Get from the database the old name of the degree type *****/
    if (!DT_GetDataOfDegreeTypeByCod (DT_EditingDegTyp))
-      Lay_ShowErrorAndExit ("Code of type of degree not found.");
+      Lay_WrongDegTypExit ();
 
    /***** Check if new name is empty *****/
    if (NewNameDegTyp[0])
@@ -1045,7 +1045,7 @@ static void DT_EditingDegreeTypeConstructor (void)
   {
    /***** Pointer must be NULL *****/
    if (DT_EditingDegTyp != NULL)
-      Lay_ShowErrorAndExit ("Error initializing degree type.");
+      Lay_WrongDegTypExit ();
 
    /***** Allocate memory for degree type *****/
    if ((DT_EditingDegTyp = malloc (sizeof (*DT_EditingDegTyp))) == NULL)
diff --git a/swad_exam.c b/swad_exam.c
index 871c9ae1..fe4a1885 100644
--- a/swad_exam.c
+++ b/swad_exam.c
@@ -1745,9 +1745,8 @@ unsigned Exa_GetParamQstInd (void)
   {
    long QstInd;
 
-   QstInd = Par_GetParToLong ("QstInd");
-   if (QstInd < 0)
-      Lay_ShowErrorAndExit ("Wrong question index.");
+   if ((QstInd = Par_GetParToLong ("QstInd")) <= 0)
+      Lay_WrongQuestionIndexExit ();
 
    return (unsigned) QstInd;
   }
@@ -1769,7 +1768,7 @@ long Exa_GetQstCodFromQstInd (long ExaCod,unsigned QstInd)
 				ExaCod,
 				QstInd);
    if (QstCod <= 0)
-      Lay_ShowErrorAndExit ("Error: wrong question index.");
+      Lay_WrongQuestionIndexExit ();
 
    return QstCod;
   }
diff --git a/swad_exam_print.c b/swad_exam_print.c
index 335e4bdb..878bd751 100644
--- a/swad_exam_print.c
+++ b/swad_exam_print.c
@@ -556,7 +556,7 @@ static void ExaPrn_GenerateChoiceIndexes (struct TstPrn_PrintedQuestion *Printed
       else
          ErrorInIndex = true;
       if (ErrorInIndex)
-         Lay_ShowErrorAndExit ("Wrong index of answer.");
+         Lay_WrongAnswerIndexExit ();
 
       if (NumOpt == 0)
 	 snprintf (StrInd,sizeof (StrInd),"%u",Index);
diff --git a/swad_exam_set.c b/swad_exam_set.c
index 4829b0c2..dc67bb2c 100644
--- a/swad_exam_set.c
+++ b/swad_exam_set.c
@@ -1414,7 +1414,7 @@ void ExaSet_GetQstDataFromDB (struct Tst_Question *Question)
 	       break;
 	    case Tst_ANS_FLOAT:
 	       if (Question->Answer.NumOptions != 2)
-		  Lay_ShowErrorAndExit ("Wrong answer.");
+		  Lay_WrongAnswerExit ();
 	       Question->Answer.FloatingPoint[NumOpt] = Str_GetDoubleFromStr (row[1]);
 	       break;
 	    case Tst_ANS_TRUE_FALSE:
@@ -1426,7 +1426,7 @@ void ExaSet_GetQstDataFromDB (struct Tst_Question *Question)
 	    case Tst_ANS_TEXT:
 	       /* Check number of options */
 	       if (Question->Answer.NumOptions > Tst_MAX_OPTIONS_PER_QUESTION)
-		  Lay_ShowErrorAndExit ("Wrong answer.");
+		  Lay_WrongAnswerExit ();
 
 	       /*  Allocate space for text and feedback */
 	       if (!Tst_AllocateTextChoiceAnswer (Question,NumOpt))
diff --git a/swad_game.c b/swad_game.c
index 7fe671dc..b4d82f63 100644
--- a/swad_game.c
+++ b/swad_game.c
@@ -1801,9 +1801,8 @@ unsigned Gam_GetParamQstInd (void)
   {
    long QstInd;
 
-   QstInd = Par_GetParToLong ("QstInd");
-   if (QstInd < 0)
-      Lay_ShowErrorAndExit ("Wrong question index.");
+   if ((QstInd = Par_GetParToLong ("QstInd")) <= 0)
+      Lay_WrongQuestionIndexExit ();
 
    return (unsigned) QstInd;
   }
@@ -1859,7 +1858,7 @@ long Gam_GetQstCodFromQstInd (long GamCod,unsigned QstInd)
 				GamCod,
 				QstInd);
    if (QstCod <= 0)
-      Lay_ShowErrorAndExit ("Error: wrong question index.");
+      Lay_WrongQuestionIndexExit ();
 
    return QstCod;
   }
@@ -2414,7 +2413,7 @@ void Gam_MoveUpQst (void)
       /* Indexes of questions to be exchanged */
       QstIndTop = Gam_GetPrevQuestionIndexInGame (Game.GamCod,QstIndBottom);
       if (!QstIndTop)
-	 Lay_ShowErrorAndExit ("Wrong index of question.");
+	 Lay_WrongQuestionIndexExit ();
 
       /* Exchange questions */
       Gam_ExchangeQuestions (Game.GamCod,QstIndTop,QstIndBottom);
@@ -2468,7 +2467,7 @@ void Gam_MoveDownQst (void)
       /* Indexes of questions to be exchanged */
       QstIndBottom = Gam_GetNextQuestionIndexInGame (Game.GamCod,QstIndTop);
       if (!QstIndBottom)
-	 Lay_ShowErrorAndExit ("Wrong index of question.");
+	 Lay_WrongQuestionIndexExit ();
 
       /* Exchange questions */
       Gam_ExchangeQuestions (Game.GamCod,QstIndTop,QstIndBottom);
diff --git a/swad_group.c b/swad_group.c
index 7f312dfe..2fb03477 100644
--- a/swad_group.c
+++ b/swad_group.c
@@ -2840,8 +2840,8 @@ void Grp_GetListGrpTypesInThisCrs (Grp_WhichGroupTypes_t WhichGroupTypes)
          row = mysql_fetch_row (mysql_res);
 
          /* Get group type code (row[0]) */
-         if ((Gbl.Crs.Grps.GrpTypes.LstGrpTypes[NumGrpTyp].GrpTypCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-            Lay_ShowErrorAndExit ("Wrong type of group.");
+         if ((Gbl.Crs.Grps.GrpTypes.LstGrpTypes[NumGrpTyp].GrpTypCod = Str_ConvertStrCodToLongCod (row[0])) <= 0)
+            Lay_WrongGrpTypExit ();
 
          /* Get group type name (row[1]) */
          Str_Copy (Gbl.Crs.Grps.GrpTypes.LstGrpTypes[NumGrpTyp].GrpTypName,row[1],
@@ -2972,8 +2972,8 @@ void Grp_GetListGrpTypesAndGrpsInThisCrs (Grp_WhichGroupTypes_t WhichGroupTypes)
                row = mysql_fetch_row (mysql_res);
 
                /* Get group code (row[0]) */
-               if ((Grp->GrpCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-                  Lay_ShowErrorAndExit ("Wrong code of group.");
+               if ((Grp->GrpCod = Str_ConvertStrCodToLongCod (row[0])) <= 0)
+                  Lay_WrongGroupExit ();
 
                /* Get group name (row[1]) */
                Str_Copy (Grp->GrpName,row[1],sizeof (Grp->GrpName) - 1);
@@ -3123,7 +3123,7 @@ static void Grp_GetDataOfGroupTypeByCod (struct GroupType *GrpTyp)
 		       " WHERE CrsCod=%ld"
 			 " AND GrpTypCod=%ld",
 		       Gbl.Hierarchy.Crs.CrsCod,GrpTyp->GrpTypCod) != 1)
-      Lay_ShowErrorAndExit ("Error when getting type of group.");
+      Lay_WrongGrpTypExit ();
 
    /***** Get some data of group type *****/
    row = mysql_fetch_row (mysql_res);
@@ -3215,7 +3215,7 @@ void Grp_GetDataOfGroupByCod (struct GroupData *GrpDat)
 
 	 /* Get the code of the group type (row[0]) */
 	 if ((GrpDat->GrpTypCod = Str_ConvertStrCodToLongCod (row[0])) <= 0)
-	    Lay_ShowErrorAndExit ("Wrong code of type of group.");
+	    Lay_WrongGrpTypExit ();
 
 	 /* Get the code of the course (row[1]) */
 	 if ((GrpDat->CrsCod = Str_ConvertStrCodToLongCod (row[1])) <= 0)
@@ -3270,7 +3270,7 @@ static long Grp_GetTypeOfGroupOfAGroup (long GrpCod)
 				   " WHERE GrpCod=%ld",
 				   GrpCod);
    if (GrpTypCod <= 0)
-      Lay_ShowErrorAndExit ("Error when getting group.");
+      Lay_WrongGrpTypExit ();
 
    return GrpTypCod;
   }
@@ -3649,8 +3649,8 @@ static void Grp_GetLstCodGrpsUsrBelongs (long CrsCod,long GrpTypCod,
 	   NumGrp < LstGrps->NumGrps;
 	   NumGrp++)
          /* Get the code of group (row[0]) */
-         if ((LstGrps->GrpCods[NumGrp] = DB_GetNextCode (mysql_res)) < 0)
-            Lay_ShowErrorAndExit ("Wrong code of group.");
+         if ((LstGrps->GrpCods[NumGrp] = DB_GetNextCode (mysql_res)) <= 0)
+            Lay_WrongGroupExit ();
      }
 
    /***** Free structure that stores the query result *****/
@@ -3694,8 +3694,8 @@ void Grp_GetLstCodGrpsWithFileZonesIBelong (struct ListCodGrps *LstGrps)
 	   NumGrp < LstGrps->NumGrps;
 	   NumGrp++)
          /* Get the code of group */
-         if ((LstGrps->GrpCods[NumGrp] = DB_GetNextCode (mysql_res)) < 0)
-            Lay_ShowErrorAndExit ("Wrong code of group.");
+         if ((LstGrps->GrpCods[NumGrp] = DB_GetNextCode (mysql_res)) <= 0)
+            Lay_WrongGroupExit ();
      }
 
    /***** Free structure that stores the query result *****/
@@ -3991,8 +3991,8 @@ void Grp_ReqRemGroupType (void)
    unsigned NumGrps;
 
    /***** Get the code of the group type *****/
-   if ((Gbl.Crs.Grps.GrpTyp.GrpTypCod = Grp_GetParamGrpTypCod ()) < 0)
-      Lay_ShowErrorAndExit ("Code of group is missing.");
+   if ((Gbl.Crs.Grps.GrpTyp.GrpTypCod = Grp_GetParamGrpTypCod ()) <= 0)
+      Lay_WrongGrpTypExit ();
 
    /***** Check if this group type has groups *****/
    if ((NumGrps = Grp_CountNumGrpsInThisCrsOfType (Gbl.Crs.Grps.GrpTyp.GrpTypCod)))	// Group type has groups ==> Ask for confirmation
@@ -4008,8 +4008,8 @@ void Grp_ReqRemGroupType (void)
 void Grp_ReqRemGroup (void)
   {
    /***** Get group code *****/
-   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of group is missing.");
+   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) <= 0)
+      Lay_WrongGroupExit ();
 
    /***** Confirm removing *****/
    Grp_AskConfirmRemGrp ();
@@ -4105,8 +4105,8 @@ static void Grp_AskConfirmRemGrp (void)
 void Grp_RemoveGroupType (void)
   {
    /***** Get param with code of group type *****/
-   if ((Gbl.Crs.Grps.GrpTyp.GrpTypCod = Grp_GetParamGrpTypCod ()) < 0)
-      Lay_ShowErrorAndExit ("Code of type of group is missing.");
+   if ((Gbl.Crs.Grps.GrpTyp.GrpTypCod = Grp_GetParamGrpTypCod ()) <= 0)
+      Lay_WrongGrpTypExit ();
 
    /***** Remove group type and its groups *****/
    Grp_RemoveGroupTypeCompletely ();
@@ -4119,8 +4119,8 @@ void Grp_RemoveGroupType (void)
 void Grp_RemoveGroup (void)
   {
    /***** Get param with group code *****/
-   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of group is missing.");
+   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) <= 0)
+      Lay_WrongGroupExit ();
 
    /***** Remove group *****/
    Grp_RemoveGroupCompletely ();
@@ -4261,8 +4261,8 @@ void Grp_OpenGroup (void)
    char AlertTxt[256 + Grp_MAX_BYTES_GROUP_NAME];
 
    /***** Get group code *****/
-   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) == -1)
-      Lay_ShowErrorAndExit ("Code of group is missing.");
+   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) <= 0)
+      Lay_WrongGroupExit ();
 
    /***** Get group data from database *****/
    GrpDat.GrpCod = Gbl.Crs.Grps.GrpCod;
@@ -4296,8 +4296,8 @@ void Grp_CloseGroup (void)
    char AlertTxt[256 + Grp_MAX_BYTES_GROUP_NAME];
 
    /***** Get group code *****/
-   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) == -1)
-      Lay_ShowErrorAndExit ("Code of group is missing.");
+   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) <= 0)
+      Lay_WrongGroupExit ();
 
    /***** Get group data from database *****/
    GrpDat.GrpCod = Gbl.Crs.Grps.GrpCod;
@@ -4331,8 +4331,8 @@ void Grp_EnableFileZonesGrp (void)
    char AlertTxt[256 + Grp_MAX_BYTES_GROUP_NAME];
 
    /***** Get group code *****/
-   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) == -1)
-      Lay_ShowErrorAndExit ("Code of group is missing.");
+   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) <= 0)
+      Lay_WrongGroupExit ();
 
    /***** Get group data from database *****/
    GrpDat.GrpCod = Gbl.Crs.Grps.GrpCod;
@@ -4367,8 +4367,8 @@ void Grp_DisableFileZonesGrp (void)
    char AlertTxt[256 + Grp_MAX_BYTES_GROUP_NAME];
 
    /***** Get group code *****/
-   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) == -1)
-      Lay_ShowErrorAndExit ("Code of group is missing.");
+   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) <= 0)
+      Lay_WrongGroupExit ();
 
    /***** Get group data from database *****/
    GrpDat.GrpCod = Gbl.Crs.Grps.GrpCod;
@@ -4407,8 +4407,8 @@ void Grp_ChangeGroupType (void)
 
    /***** Get parameters from form *****/
    /* Get group code */
-   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of group is missing.");
+   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) <= 0)
+      Lay_WrongGroupExit ();
 
    /* Get the new group type */
    NewGrpTypCod = Grp_GetParamGrpTypCod ();
@@ -4461,8 +4461,8 @@ void Grp_ChangeGroupRoom (void)
 
    /***** Get parameters from form *****/
    /* Get group code */
-   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of group is missing.");
+   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) <= 0)
+      Lay_WrongGroupExit ();
 
    /* Get the new room */
    NewRooCod = Roo_GetParamRooCod ();
@@ -4506,8 +4506,8 @@ void Grp_ChangeMandatGrpTyp (void)
 
    /***** Get parameters of the form *****/
    /* Get the código of type of group */
-   if ((Gbl.Crs.Grps.GrpTyp.GrpTypCod = Grp_GetParamGrpTypCod ()) < 0)
-      Lay_ShowErrorAndExit ("Code of type of group is missing.");
+   if ((Gbl.Crs.Grps.GrpTyp.GrpTypCod = Grp_GetParamGrpTypCod ()) <= 0)
+      Lay_WrongGrpTypExit ();
 
    /* Get the new type of enrolment (mandatory or voluntaria) of this type of group */
    NewMandatoryEnrolment = Par_GetParToBool ("MandatoryEnrolment");
@@ -4564,8 +4564,8 @@ void Grp_ChangeMultiGrpTyp (void)
 
    /***** Get parameters from the form *****/
    /* Get the code of type of group */
-   if ((Gbl.Crs.Grps.GrpTyp.GrpTypCod = Grp_GetParamGrpTypCod ()) < 0)
-      Lay_ShowErrorAndExit ("Code of type of group is missing.");
+   if ((Gbl.Crs.Grps.GrpTyp.GrpTypCod = Grp_GetParamGrpTypCod ()) <= 0)
+      Lay_WrongGrpTypExit ();
 
    /* Get the new type of enrolment (single or multiple) of this type of group */
    NewMultipleEnrolment = Par_GetParToBool ("MultipleEnrolment");
@@ -4616,8 +4616,8 @@ void Grp_ChangeOpenTimeGrpTyp (void)
    extern const char *Txt_The_date_time_of_opening_of_groups_has_changed;
 
    /***** Get the code of type of group *****/
-   if ((Gbl.Crs.Grps.GrpTyp.GrpTypCod = Grp_GetParamGrpTypCod ()) < 0)
-      Lay_ShowErrorAndExit ("Code of type of group is missing.");
+   if ((Gbl.Crs.Grps.GrpTyp.GrpTypCod = Grp_GetParamGrpTypCod ()) <= 0)
+      Lay_WrongGrpTypExit ();
 
    /***** Get from the database the data of this type of group *****/
    Grp_GetDataOfGroupTypeByCod (&Gbl.Crs.Grps.GrpTyp);
@@ -4662,8 +4662,8 @@ void Grp_ChangeMaxStdsGrp (void)
 
    /***** Get parameters of the form *****/
    /* Get group code */
-   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) == -1)
-      Lay_ShowErrorAndExit ("Code of group is missing.");
+   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) <= 0)
+      Lay_WrongGroupExit ();
 
    /* Get the new maximum number of students of the group */
    NewMaxStds = (unsigned)
@@ -4757,8 +4757,8 @@ void Grp_RenameGroupType (void)
 
    /***** Get parameters from form *****/
    /* Get the code of the group type */
-   if ((Gbl.Crs.Grps.GrpTyp.GrpTypCod = Grp_GetParamGrpTypCod ()) < 0)
-      Lay_ShowErrorAndExit ("Code of type of group is missing.");
+   if ((Gbl.Crs.Grps.GrpTyp.GrpTypCod = Grp_GetParamGrpTypCod ()) <= 0)
+      Lay_WrongGrpTypExit ();
 
    /* Get the new name for the group type */
    Par_GetParToText ("GrpTypName",NewNameGrpTyp,Grp_MAX_BYTES_GROUP_TYPE_NAME);
@@ -4836,8 +4836,8 @@ void Grp_RenameGroup (void)
 
    /***** Get parameters from form *****/
    /* Get the code of the group */
-   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of group is missing.");
+   if ((Gbl.Crs.Grps.GrpCod = Grp_GetParamGrpCod ()) <= 0)
+      Lay_WrongGroupExit ();
 
    /* Get the new name for the group */
    Par_GetParToText ("GrpName",NewNameGrp,Grp_MAX_BYTES_GROUP_NAME);
diff --git a/swad_layout.c b/swad_layout.c
index d2e06eb5..f56d4f73 100644
--- a/swad_layout.c
+++ b/swad_layout.c
@@ -1407,6 +1407,11 @@ void Lay_WrongCenterExit (void)
    Lay_ShowErrorAndExit ("Wrong center.");
   }
 
+void Lay_WrongDegTypExit (void)
+  {
+   Lay_ShowErrorAndExit ("Wrong degree type.");
+  }
+
 void Lay_WrongDegreeExit (void)
   {
    Lay_ShowErrorAndExit ("Wrong degree.");
@@ -1426,6 +1431,20 @@ void Lay_WrongOrderExit (void)
    Lay_ShowErrorAndExit ("Wrong order.");
   }
 
+/*****************************************************************************/
+/********* Write error message and exit when wrong group type/group **********/
+/*****************************************************************************/
+
+void Lay_WrongGrpTypExit (void)
+  {
+   Lay_ShowErrorAndExit ("Wrong group type.");
+  }
+
+void Lay_WrongGroupExit (void)
+  {
+   Lay_ShowErrorAndExit ("Wrong group.");
+  }
+
 /*****************************************************************************/
 /************* Write error message and exit when wrong order *****************/
 /*****************************************************************************/
@@ -1435,6 +1454,33 @@ void Lay_WrongTypeOfViewExit (void)
    Lay_ShowErrorAndExit ("Wrong type of view.");
   }
 
+/*****************************************************************************/
+/************* Write error message and exit when wrong banner ****************/
+/*****************************************************************************/
+
+void Lay_WrongBannerExit (void)
+  {
+   Lay_ShowErrorAndExit ("Wrong banner.");
+  }
+
+/*****************************************************************************/
+/************ Write error message and exit when wrong building ***************/
+/*****************************************************************************/
+
+void Lay_WrongBuildingExit (void)
+  {
+   Lay_ShowErrorAndExit ("Wrong building.");
+  }
+
+/*****************************************************************************/
+/*********** Write error message and exit when wrong assignment **************/
+/*****************************************************************************/
+
+void Lay_WrongAssignmentExit (void)
+  {
+   Lay_ShowErrorAndExit ("Wrong assignment.");
+  }
+
 /*****************************************************************************/
 /************* Write error message and exit when wrong project ***************/
 /*****************************************************************************/
@@ -1480,6 +1526,25 @@ void Lay_WrongQuestionExit (void)
    Lay_ShowErrorAndExit ("Wrong question.");
   }
 
+void Lay_WrongQuestionIndexExit (void)
+  {
+   Lay_ShowErrorAndExit ("Wrong question index.");
+  }
+
+/*****************************************************************************/
+/************** Write error message and exit when wrong answer ***************/
+/*****************************************************************************/
+
+void Lay_WrongAnswerExit (void)
+  {
+   Lay_ShowErrorAndExit ("Wrong answer.");
+  }
+
+void Lay_WrongAnswerIndexExit (void)
+  {
+   Lay_ShowErrorAndExit ("Wrong answer index.");
+  }
+
 /*****************************************************************************/
 /*********** Write error message and exit when wrong exam session ************/
 /*****************************************************************************/
@@ -1503,6 +1568,15 @@ void Lay_WrongMatchExit (void)
    Lay_ShowErrorAndExit ("Wrong match.");
   }
 
+/*****************************************************************************/
+/************** Write error message and exit when wrong survey ***************/
+/*****************************************************************************/
+
+void Lay_WrongSurveyExit (void)
+  {
+   Lay_ShowErrorAndExit ("Wrong survey.");
+  }
+
 /*****************************************************************************/
 /*** Write error message and exit when wrong parameter "who" (which users) ***/
 /*****************************************************************************/
diff --git a/swad_layout.h b/swad_layout.h
index 4ef32ef7..6f554067 100644
--- a/swad_layout.h
+++ b/swad_layout.h
@@ -74,18 +74,28 @@ void Lay_WrongScopeExit (void);
 void Lay_WrongCountrExit (void);
 void Lay_WrongInstitExit (void);
 void Lay_WrongCenterExit (void);
+void Lay_WrongDegTypExit (void);
 void Lay_WrongDegreeExit (void);
 void Lay_WrongCourseExit (void);
 void Lay_WrongOrderExit (void);
+void Lay_WrongGrpTypExit (void);
+void Lay_WrongGroupExit (void);
 void Lay_WrongTypeOfViewExit (void);
+void Lay_WrongBannerExit (void);
+void Lay_WrongBuildingExit (void);
+void Lay_WrongAssignmentExit (void);
 void Lay_WrongProjectExit (void);
 void Lay_WrongCallForExamExit (void);
 void Lay_WrongExamExit (void);
 void Lay_WrongSetExit (void);
 void Lay_WrongQuestionExit (void);
+void Lay_WrongQuestionIndexExit (void);
+void Lay_WrongAnswerExit (void);
+void Lay_WrongAnswerIndexExit (void);
 void Lay_WrongExamSessionExit (void);
 void Lay_WrongGameExit (void);
 void Lay_WrongMatchExit (void);
+void Lay_WrongSurveyExit (void);
 void Lay_WrongWhoExit (void);
 void Lay_WrongEventExit (void);
 void Lay_WrongUserExit (void);
diff --git a/swad_survey.c b/swad_survey.c
index e9041ed1..3285d5fc 100644
--- a/swad_survey.c
+++ b/swad_survey.c
@@ -433,8 +433,8 @@ void Svy_SeeOneSurvey (void)
    Surveys.CurrentPage = Pag_GetParamPagNum (Pag_SURVEYS);
 
    /***** Get survey code *****/
-   if ((Svy.SvyCod = Svy_GetParamSvyCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of survey is missing.");
+   if ((Svy.SvyCod = Svy_GetParamSvyCod ()) <= 0)
+      Lay_WrongSurveyExit ();
 
    /***** Show survey *****/
    Svy_ShowOneSurvey (&Surveys,Svy.SvyCod,true);
@@ -650,7 +650,7 @@ static void Svy_ShowOneSurvey (struct Svy_Surveys *Surveys,
    switch (Svy.Scope)
      {
       case Hie_Lvl_UNK:	// Unknown
-         Lay_ShowErrorAndExit ("Wrong survey scope.");
+         Lay_WrongScopeExit ();
          break;
       case Hie_Lvl_SYS:	// System
          HTM_Txt (Cfg_PLATFORM_SHORT_NAME);
@@ -1068,7 +1068,7 @@ static void Svy_GetListSurveys (struct Svy_Surveys *Surveys)
 	   NumSvy++)
          /* Get next survey code */
          if ((Surveys->LstSvyCods[NumSvy] = DB_GetNextCode (mysql_res)) < 0)
-            Lay_ShowErrorAndExit ("Error: wrong survey code.");
+            Lay_WrongSurveyExit ();
      }
    else
       Surveys->Num = 0;
@@ -1573,8 +1573,8 @@ void Svy_AskRemSurvey (void)
    Surveys.CurrentPage = Pag_GetParamPagNum (Pag_SURVEYS);
 
    /***** Get survey code *****/
-   if ((Svy.SvyCod = Svy_GetParamSvyCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of survey is missing.");
+   if ((Svy.SvyCod = Svy_GetParamSvyCod ()) <= 0)
+      Lay_WrongSurveyExit ();
 
    /***** Get data of the survey from database *****/
    Svy_GetDataOfSurveyByCod (&Svy);
@@ -1612,8 +1612,8 @@ void Svy_RemoveSurvey (void)
    Surveys.CurrentPage = Pag_GetParamPagNum (Pag_SURVEYS);
 
    /***** Get survey code *****/
-   if ((Svy.SvyCod = Svy_GetParamSvyCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of survey is missing.");
+   if ((Svy.SvyCod = Svy_GetParamSvyCod ()) <= 0)
+      Lay_WrongSurveyExit ();
 
    /***** Get data of the survey from database *****/
    Svy_GetDataOfSurveyByCod (&Svy);
@@ -1680,8 +1680,8 @@ void Svy_AskResetSurvey (void)
    Surveys.CurrentPage = Pag_GetParamPagNum (Pag_SURVEYS);
 
    /***** Get survey code *****/
-   if ((Svy.SvyCod = Svy_GetParamSvyCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of survey is missing.");
+   if ((Svy.SvyCod = Svy_GetParamSvyCod ()) <= 0)
+      Lay_WrongSurveyExit ();
 
    /***** Get data of the survey from database *****/
    Svy_GetDataOfSurveyByCod (&Svy);
@@ -1733,8 +1733,8 @@ void Svy_ResetSurvey (void)
    Surveys.CurrentPage = Pag_GetParamPagNum (Pag_SURVEYS);
 
    /***** Get survey code *****/
-   if ((Svy.SvyCod = Svy_GetParamSvyCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of survey is missing.");
+   if ((Svy.SvyCod = Svy_GetParamSvyCod ()) <= 0)
+      Lay_WrongSurveyExit ();
 
    /***** Get data of the survey from database *****/
    Svy_GetDataOfSurveyByCod (&Svy);
@@ -1782,8 +1782,8 @@ void Svy_HideSurvey (void)
    Surveys.CurrentPage = Pag_GetParamPagNum (Pag_SURVEYS);
 
    /***** Get survey code *****/
-   if ((Svy.SvyCod = Svy_GetParamSvyCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of survey is missing.");
+   if ((Svy.SvyCod = Svy_GetParamSvyCod ()) <= 0)
+      Lay_WrongSurveyExit ();
 
    /***** Get data of the survey from database *****/
    Svy_GetDataOfSurveyByCod (&Svy);
@@ -1819,8 +1819,8 @@ void Svy_UnhideSurvey (void)
    Surveys.CurrentPage = Pag_GetParamPagNum (Pag_SURVEYS);
 
    /***** Get survey code *****/
-   if ((Svy.SvyCod = Svy_GetParamSvyCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of survey is missing.");
+   if ((Svy.SvyCod = Svy_GetParamSvyCod ()) <= 0)
+      Lay_WrongSurveyExit ();
 
    /***** Get data of the survey from database *****/
    Svy_GetDataOfSurveyByCod (&Svy);
@@ -2685,8 +2685,8 @@ void Svy_RequestEditQuestion (void)
    Txt[0] = '\0';
 
    /***** Get survey code *****/
-   if ((SvyCod = Svy_GetParamSvyCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of survey is missing.");
+   if ((SvyCod = Svy_GetParamSvyCod ()) <= 0)
+      Lay_WrongSurveyExit ();
 
    /* Get the question code */
    SvyQst.QstCod = Svy_GetParamQstCod ();
@@ -2747,7 +2747,7 @@ static void Svy_ShowFormEditOneQst (struct Svy_Surveys *Surveys,
 
          /* Get question index inside survey (row[0]) */
          if (sscanf (row[0],"%u",&(SvyQst->QstInd)) != 1)
-            Lay_ShowErrorAndExit ("Error: wrong question index.");
+            Lay_WrongQuestionIndexExit ();
 
          /* Get the type of answer (row[1]) */
          SvyQst->AnswerType = Svy_ConvertFromStrAnsTypDBToAnsTyp (row[1]);
@@ -3083,8 +3083,8 @@ void Svy_ReceiveQst (void)
 
    /***** Get parameters from form *****/
    /* Get survey code */
-   if ((SvyCod = Svy_GetParamSvyCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of survey is missing.");
+   if ((SvyCod = Svy_GetParamSvyCod ()) <= 0)
+      Lay_WrongSurveyExit ();
 
    /* Get question code */
    SvyQst.QstCod = Svy_GetParamQstCod ();
@@ -3363,47 +3363,47 @@ static void Svy_ListSvyQuestions (struct Svy_Surveys *Surveys,
 
          /* row[0] holds the code of the question */
          if (sscanf (row[0],"%ld",&(SvyQst.QstCod)) != 1)
-            Lay_ShowErrorAndExit ("Wrong code of question.");
+            Lay_WrongQuestionExit ();
 
          HTM_TR_Begin (NULL);
 
-         if (Svy->Status.ICanEdit)
-           {
-	    HTM_TD_Begin ("class=\"BT%u\"",Gbl.RowEvenOdd);
+	    if (Svy->Status.ICanEdit)
+	      {
+	       HTM_TD_Begin ("class=\"BT%u\"",Gbl.RowEvenOdd);
 
-	    /* Initialize context */
-            Surveys->SvyCod = Svy->SvyCod;
-            Surveys->QstCod = SvyQst.QstCod;
+		  /* Initialize context */
+		  Surveys->SvyCod = Svy->SvyCod;
+		  Surveys->QstCod = SvyQst.QstCod;
 
-            /* Write icon to remove the question */
-	    Ico_PutContextualIconToRemove (ActReqRemSvyQst,NULL,
-					   Svy_PutParamsToEditQuestion,Surveys);
+		  /* Write icon to remove the question */
+		  Ico_PutContextualIconToRemove (ActReqRemSvyQst,NULL,
+						 Svy_PutParamsToEditQuestion,Surveys);
 
-            /* Write icon to edit the question */
-            Ico_PutContextualIconToEdit (ActEdiOneSvyQst,NULL,
-                                         Svy_PutParamsToEditQuestion,Surveys);
+		  /* Write icon to edit the question */
+		  Ico_PutContextualIconToEdit (ActEdiOneSvyQst,NULL,
+					       Svy_PutParamsToEditQuestion,Surveys);
 
-            HTM_TD_End ();
-           }
+	       HTM_TD_End ();
+	      }
 
-         /* Write index of question inside survey (row[1]) */
-         if (sscanf (row[1],"%u",&(SvyQst.QstInd)) != 1)
-            Lay_ShowErrorAndExit ("Error: wrong question index.");
-         HTM_TD_Begin ("class=\"DAT_SMALL CT COLOR%u\"",Gbl.RowEvenOdd);
-         HTM_Unsigned (SvyQst.QstInd + 1);
-         HTM_TD_End ();
+	    /* Write index of question inside survey (row[1]) */
+	    HTM_TD_Begin ("class=\"DAT_SMALL CT COLOR%u\"",Gbl.RowEvenOdd);
+	       if (sscanf (row[1],"%u",&(SvyQst.QstInd)) != 1)
+		  Lay_WrongQuestionIndexExit ();
+	       HTM_Unsigned (SvyQst.QstInd + 1);
+	    HTM_TD_End ();
 
-         /* Write the question type (row[2]) */
-         SvyQst.AnswerType = Svy_ConvertFromStrAnsTypDBToAnsTyp (row[2]);
-         HTM_TD_Begin ("class=\"DAT_SMALL CT COLOR%u\"",Gbl.RowEvenOdd);
-         HTM_Txt (Txt_SURVEY_STR_ANSWER_TYPES[SvyQst.AnswerType]);
-         HTM_TD_End ();
+	    /* Write the question type (row[2]) */
+	    HTM_TD_Begin ("class=\"DAT_SMALL CT COLOR%u\"",Gbl.RowEvenOdd);
+	       SvyQst.AnswerType = Svy_ConvertFromStrAnsTypDBToAnsTyp (row[2]);
+	       HTM_Txt (Txt_SURVEY_STR_ANSWER_TYPES[SvyQst.AnswerType]);
+	    HTM_TD_End ();
 
-         /* Write the stem (row[3]) and the answers of this question */
-         HTM_TD_Begin ("class=\"DAT LT COLOR%u\"",Gbl.RowEvenOdd);
-         Svy_WriteQstStem (row[3]);
-         Svy_WriteAnswersOfAQst (Svy,&SvyQst,PutFormAnswerSurvey);
-         HTM_TD_End ();
+	    /* Write the stem (row[3]) and the answers of this question */
+	    HTM_TD_Begin ("class=\"DAT LT COLOR%u\"",Gbl.RowEvenOdd);
+	       Svy_WriteQstStem (row[3]);
+	       Svy_WriteAnswersOfAQst (Svy,&SvyQst,PutFormAnswerSurvey);
+	    HTM_TD_End ();
 
          HTM_TR_End ();
         }
@@ -3695,8 +3695,8 @@ void Svy_RequestRemoveQst (void)
 
    /***** Get parameters from form *****/
    /* Get survey code */
-   if ((SvyCod = Svy_GetParamSvyCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of survey is missing.");
+   if ((SvyCod = Svy_GetParamSvyCod ()) <= 0)
+      Lay_WrongSurveyExit ();
 
    /* Get question code */
    if ((SvyQst.QstCod = Svy_GetParamQstCod ()) < 0)
@@ -3737,11 +3737,11 @@ void Svy_RemoveQst (void)
 
    /***** Get parameters from form *****/
    /* Get survey code */
-   if ((SvyCod = Svy_GetParamSvyCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of survey is missing.");
+   if ((SvyCod = Svy_GetParamSvyCod ()) <= 0)
+      Lay_WrongSurveyExit ();
 
    /* Get question code */
-   if ((SvyQst.QstCod = Svy_GetParamQstCod ()) < 0)
+   if ((SvyQst.QstCod = Svy_GetParamQstCod ()) <= 0)
       Lay_WrongQuestionExit ();
 
    /* Get question index */
@@ -3790,8 +3790,8 @@ void Svy_ReceiveSurveyAnswers (void)
    Svy_ResetSurveys (&Surveys);
 
    /***** Get survey code *****/
-   if ((Svy.SvyCod = Svy_GetParamSvyCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of survey is missing.");
+   if ((Svy.SvyCod = Svy_GetParamSvyCod ()) <= 0)
+      Lay_WrongSurveyExit ();
 
    /***** Get data of the survey from database *****/
    Svy_GetDataOfSurveyByCod (&Svy);