title: customvalidator onServerValidate not firing
body: <p>I have a Radio button List and Text Box both with validation.</p>
  
  <pre><code>&lt;asp:RadioButtonList ID="member" runat="server" RepeatDirection="Horizontal"&gt;
      &lt;asp:ListItem&gt;Yes&lt;/asp:ListItem&gt;
      &lt;asp:ListItem&gt;No&lt;/asp:ListItem&gt;
  &lt;/asp:RadioButtonList&gt;
  
  &lt;asp:requiredfieldvalidator id="unionvalidator" runat="server" controltovalidate="member" errormessage="Required" /&gt;
  
  Required if member == "yes"
  
  &lt;asp:TextBox runat="server" ID="union"&gt;&lt;/asp:TextBox&gt;
  &lt;asp:customvalidator ID="Customvalidator1" runat="server" ValidateEmptyText="true" onServerValidate="UnionValidate" errormessage="Your current union is required"  /&gt;
  </code></pre>
  
  <p>My ServerValidate which doesn't fire at all.</p>
  
  <pre><code>public void UnionValidate(object source, ServerValidateEventArgs args)
  {
      if (member.Text == "yes" &amp;&amp; union.Text.Trim() == "")
          args.IsValid = false;
  }
  </code></pre>