title: Error Panel Row Updating
body: <p>I want to show error panel on row updating but it does not show the error panel. What's wrong with this code?</p>
  
  <pre><code>protected void Grades_GridView_RowUpdating(object sender, GridViewUpdateEventArgs e)
  {  
      string LetterGrade = Grades_GridView.DataKeys[e.RowIndex].Values["Letter_Grade"].ToString();
      TextBox txtMinGrade = (TextBox)Grades_GridView.Rows[e.RowIndex].FindControl("txtMinGrade");
      TextBox txtMaxGrade = (TextBox)Grades_GridView.Rows[e.RowIndex].FindControl("txtMaxGrade");
  
      if (Convert.ToDecimal(txtMinGrade.Text) &gt; Convert.ToDecimal(txtMaxGrade.Text))
      {
          PanelError.Visible = true;
          LabelErrorString.Text = "Minimum grade must not be greater than maximum grade!";     
      }
      else
      {
          Admin.updateGradeRanges(LetterGrade, txtMinGrade.Text, txtMaxGrade.Text);
      }
      Grades_GridView.EditIndex = -1;
      FillGradeRangesInGrid();
  }
  </code></pre>