title: ASP.NET AJAX Control Toolkit ValidatorCallout not working on edit template
body: <p>I have a page that has a listview that is used for inserting and editing records.
  Assigning a RequiredFieldValidator and ValidatorCallOutExtender to the InsertItemTemplate works well.<br>
  When I try to do the same on the EditItemTemplate the ValidatorCallOut appears but with no text in the box.
  Is there something that I'm doing wrong?</p>
  
  <p>My code for the InsertItemTemplate:</p>
  
  <pre><code> &lt;asp:TextBox ID="date_timeTextBox" runat="server" Text='&lt;%# Bind("date_time") %&gt;' /&gt;
   &lt;asp:RequiredFieldValidator 
        ControlToValidate="date_timeTextBox" 
        ID="RequiredFieldValidator1" 
        runat="server" 
        ErrorMessage="date_time is required" 
        Display="None" 
        ValidationGroup="insert_into"&gt;
   &lt;/asp:RequiredFieldValidator&gt;
   &lt;cc1:ValidatorCalloutExtender ID="ValidatorCalloutExtender1" 
        runat="server" 
        TargetControlID="RequiredFieldValidator1"&gt;
   &lt;/cc1:ValidatorCalloutExtender&gt;
  </code></pre>
  
  <p>And for the EditItemTemplate:</p>
  
  <pre><code>&lt;asp:TextBox 
      ID="date_timeTextBox" 
      runat="server" 
      Text='&lt;%# Bind("date_time","{0:yyyy-MM-dd}") %&gt;' /&gt;
  &lt;asp:RequiredFieldValidator 
      ControlToValidate="date_timeTextBox" 
      ID="reqDTT"       
      runat="server" 
      ErrorMessage="date_time is required" 
      Display="None" 
      ValidationGroup="edit_validate"&gt;
  &lt;/asp:RequiredFieldValidator&gt;
  &lt;cc1:ValidatorCalloutExtender 
      ID="val_reqDTT" 
      runat="server" 
      TargetControlID="reqDTT"&gt;
  &lt;/cc1:ValidatorCalloutExtender&gt;
  </code></pre>