title: ASP Validators not working?
body: <p>I feel embarrassed to be posting this as I'm pretty sure I'm missing something really simple, and this certainly isn't the first time I've used asp validators. I have the following validator controls:</p>
  
  <pre><code>&lt;asp:RequiredFieldValidator runat="server" ControlToValidate="txtTitle" EnableClientScript="false" ErrorMessage="*" ValidationGroup="groupUpdateAL" /&gt;
  
  &lt;asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" ControlToValidate="txtAbbr" EnableClientScript="false" ErrorMessage="*" ValidationGroup="groupUpdateAL" /&gt;
  
  &lt;asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="ddlColour" EnableClientScript="false" ValidationGroup="groupUpdateAL" ErrorMessage="*" /&gt;
  
  &lt;asp:Button ID="btnSave" runat="server" Text="Save" ValidationGroup="groupUpdateAL" CausesValidation="true" /&gt;&lt;br /&gt;
  </code></pre>
  
  <p>For some reason, if leaving the controls empty I am given the following error:</p>
  
  <pre><code>Length cannot be less than zero.
  Parameter name: length
  </code></pre>
  
  <p>It seems the validation controls aren't catching an invalid input.</p>
  
  <p><strong>What I've Tried:</strong></p>
  
  <p>I suspected it may have been client validation intercepting the postback, which is why you can see EnableClientScript is set to false now. Didn't work.</p>