title: ASP.NET Required Field Validator not working
body: <p>Hi all I need a required field validator for my textbox..This is my textbox..</p>
  
  <pre><code>&lt;asp:TextBox ID="txtTimeSlotGroupName" runat="server" AutoPostBack="false" 
       ClientIDMode="Static"&gt;&lt;/asp:TextBox&gt;  
  &lt;font color="red"&gt;*&lt;/font&gt;  
  &lt;asp:RequiredFieldValidator ID="RequiredFieldValidator_txtTimeSlotGroupName"
       runat="server" ControlToValidate="txtTimeSlotGroupName" Display="None"
       ErrorMessage="Timeslot Group Required!" ForeColor="Red" InitialValue="0"
       ValidationGroup="TimeSlot"&gt;&lt;/asp:RequiredFieldValidator&gt;
  </code></pre>
  
  <p><strong>My button:</strong></p>
  
  <pre><code>&lt;asp:Button ID="btnAddTimeSlots" Text="Add Timeslots" CssClass="button" 
       runat="server" OnClick="btnAddTimeslots_Click" ValidationGroup="TimeSlot" 
       OnClientClick="javascript:shouldsubmit=true;"/&gt;
  </code></pre>
  
  <p>I am not getting the error message. Any solutions?</p>