diff --git a/swad_changelog.h b/swad_changelog.h
index 1245e550..7fb56a7a 100644
--- a/swad_changelog.h
+++ b/swad_changelog.h
@@ -487,7 +487,7 @@ enscript -2 --landscape --color --file-align=2 --highlight --line-numbers -o - *
 En OpenSWAD:
 ps2pdf source.ps destination.pdf
 */
-#define Log_PLATFORM_VERSION	"SWAD 19.33.5 (2019-10-13)"
+#define Log_PLATFORM_VERSION	"SWAD 19.33.7 (2019-10-13)"
 #define CSS_FILE		"swad19.33.css"
 #define JS_FILE			"swad19.30.js"
 /*
@@ -496,6 +496,8 @@ ps2pdf source.ps destination.pdf
 // TODO: En un TFG no preasignado con estudiante tiene que salir un triángulo amarillo
 // TODO: Hacer un nuevo rol en los TFG: tutor externo (profesor de áreas no vinculadas con el centro, profesionales de empresas, etc.)
 
+	Version 19.33.7:  Oct 13, 2019	Fixed bug in surveys. (245317 lines)
+	Version 19.33.6:  Oct 13, 2019	Fixed bug in exam announcements. (245299 lines)
 	Version 19.33.5:  Oct 13, 2019	Fixed bug in file browser. (245298 lines)
 	Version 19.33.4:  Oct 13, 2019	Code refactoring in HTML table headings. (245291 lines)
 	Version 19.33.3:  Oct 13, 2019	Code refactoring in HTML table headings. (245499 lines)
diff --git a/swad_exam.c b/swad_exam.c
index 03e8c8a7..8b25ee1d 100644
--- a/swad_exam.c
+++ b/swad_exam.c
@@ -1040,8 +1040,8 @@ static void Exa_ShowExamAnnouncement (long ExaCod,
      }
 
    /***** Start table *****/
-   Tbl_TABLE_Begin ("%s CELLS_PAD_2\">",
-                        ClassExaAnnouncement[TypeViewExamAnnouncement][Gbl.ExamAnns.ExaDat.Status]);
+   Tbl_TABLE_Begin ("%s CELLS_PAD_2",
+                    ClassExaAnnouncement[TypeViewExamAnnouncement][Gbl.ExamAnns.ExaDat.Status]);
 
    /***** Institution logo *****/
    Tbl_TR_Begin (NULL);
diff --git a/swad_survey.c b/swad_survey.c
index a816b37c..3a77cccf 100644
--- a/swad_survey.c
+++ b/swad_survey.c
@@ -3278,6 +3278,7 @@ static void Svy_ListSvyQuestions (struct Survey *Svy,
          Svy_WriteQstStem (row[3]);
          Svy_WriteAnswersOfAQst (Svy,SvyQst,PutFormAnswerSurvey);
          Tbl_TD_End ();
+
          Tbl_TR_End ();
         }
 
@@ -3396,6 +3397,7 @@ static void Svy_WriteAnswersOfAQst (struct Survey *Svy,
 
       /* Write one row for each answer */
       Tbl_TABLE_BeginPadding (5);
+
       for (NumAns = 0;
 	   NumAns < NumAnswers;
 	   NumAns++)
@@ -3461,6 +3463,7 @@ static void Svy_WriteAnswersOfAQst (struct Survey *Svy,
 	 /* Free memory allocated for the answer */
 	 Svy_FreeTextChoiceAnswer (SvyQst,NumAns);
 	}
+
       Tbl_TABLE_End ();
      }
 
@@ -3491,8 +3494,9 @@ static void Svy_DrawBarNumUsrs (unsigned NumUsrs,unsigned MaxUsrs)
 	        "0&nbsp;(0%%&nbsp;%s&nbsp;%u)",
                 Txt_of_PART_OF_A_TOTAL,MaxUsrs);
 
-   /***** Draw bar with a with proportional to the number of clicks *****/
    Tbl_TD_Begin ("class=\"DAT LEFT_TOP\" style=\"width:%upx;\"",Svy_MAX_BAR_WIDTH + 125);
+
+   /***** Draw bar with a with proportional to the number of clicks *****/
    if (NumUsrs && MaxUsrs)
       BarWidth = (unsigned) ((((float) NumUsrs * (float) Svy_MAX_BAR_WIDTH) /
 	                       (float) MaxUsrs) + 0.5);
@@ -3511,9 +3515,8 @@ static void Svy_DrawBarNumUsrs (unsigned NumUsrs,unsigned MaxUsrs)
    /***** Write the number of users *****/
    fprintf (Gbl.F.Out,"%s",
             Gbl.Title);
-   Tbl_TD_End ();
 
-   Tbl_TR_End ();
+   Tbl_TD_End ();
   }
 
 /*****************************************************************************/
diff --git a/swad_table.c b/swad_table.c
index c229516c..d6104347 100644
--- a/swad_table.c
+++ b/swad_table.c
@@ -51,6 +51,14 @@ extern struct Globals Gbl;
 /******************************* Private types *******************************/
 /*****************************************************************************/
 
+/*****************************************************************************/
+/***************************** Private vatiables *****************************/
+/*****************************************************************************/
+
+static unsigned Tbl_TR_NestingLevel = 0;
+static unsigned Tbl_TH_NestingLevel = 0;
+static unsigned Tbl_TD_NestingLevel = 0;
+
 /*****************************************************************************/
 /***************************** Private prototypes ****************************/
 /*****************************************************************************/
@@ -190,6 +198,8 @@ void Tbl_TR_Begin (const char *fmt,...)
      }
    else
       Tbl_TR_BeginWithoutAttr ();
+
+   Tbl_TR_NestingLevel++;
   }
 
 static void Tbl_TR_BeginWithoutAttr (void)
@@ -199,7 +209,12 @@ static void Tbl_TR_BeginWithoutAttr (void)
 
 void Tbl_TR_End (void)
   {
+   if (Tbl_TR_NestingLevel == 0)	// No TR open
+      Lay_ShowErrorAndExit ("Trying to close unopened TR.");
+
    fprintf (Gbl.F.Out,"</tr>");
+
+   Tbl_TR_NestingLevel--;
   }
 
 /*****************************************************************************/
@@ -283,6 +298,8 @@ static void Tbl_TH_BeginAttr (const char *fmt,...)
      }
    else
       Tbl_TH_BeginWithoutAttr ();
+
+   Tbl_TH_NestingLevel++;
   }
 
 static void Tbl_TH_BeginWithoutAttr (void)
@@ -292,7 +309,12 @@ static void Tbl_TH_BeginWithoutAttr (void)
 
 void Tbl_TH_End (void)
   {
+   if (Tbl_TH_NestingLevel == 0)	// No TH open
+      Lay_ShowErrorAndExit ("Trying to close unopened TR.");
+
    fprintf (Gbl.F.Out,"</th>");
+
+   Tbl_TH_NestingLevel--;
   }
 
 void Tbl_TH_Empty (unsigned NumColumns)
@@ -341,6 +363,8 @@ void Tbl_TD_Begin (const char *fmt,...)
      }
    else
       Tbl_TD_BeginWithoutAttr ();
+
+   Tbl_TD_NestingLevel++;
   }
 
 static void Tbl_TD_BeginWithoutAttr (void)
@@ -350,7 +374,12 @@ static void Tbl_TD_BeginWithoutAttr (void)
 
 void Tbl_TD_End (void)
   {
+   if (Tbl_TD_NestingLevel == 0)	// No TH open
+      Lay_ShowErrorAndExit ("Trying to close unopened TR.");
+
    fprintf (Gbl.F.Out,"</td>");
+
+   Tbl_TD_NestingLevel--;
   }
 
 void Tbl_TD_Empty (unsigned NumColumns)