CustomValidator fires on the client but the validation control does not render when validation fails
<p>I have a simple: If the 'yes' radio button is checked than make the text box required situation.  I have supplied both client and server-side validation.  What I'm finding is that:</p>

<ol>
<li>Client validation is firing and displaying failure correctly via an alert message.</li>
<li>The validation control never renders an error message and the server is hit.</li>
<li>When the server is hit and validation fails, the control renders the proper error message.</li>
</ol>

<p>Why is the client working correctly in terms of validating, but not rendering an error message and continuing on to the server?</p>

<pre><code>asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent"&gt;
&lt;script src="Scripts/jquery-1.7.2.js" type="text/javascript"&gt;&lt;/script&gt; 

&lt;script type="text/javascript"&gt;
    function testClientValidation(src, args) {
        if ($('#&lt;%=rblstTest.ClientID%&gt;' + ' input:checked').length == 1) {
            if ($('#&lt;%=rblstTest.ClientID%&gt;' + ' input:checked').val().toLowerCase() == "yes") {
                args.isValid = !($('#&lt;%=txtTest.ClientID%&gt;').val() == "");  
            } else {
                args.isValid = true;
            }
        } else {
            args.isValid = true;
        }

        alert(args.isValid);
    }
&lt;/script&gt;
&lt;/asp:Content&gt;
&lt;asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent"&gt;
&lt;div&gt;
&lt;asp:RadioButtonList ID="rblstTest" RepeatDirection="Horizontal" RepeatLayout="Flow" runat="server"&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:TextBox ID="txtTest" runat="server"/&gt;

&lt;asp:CustomValidator ID="cust" ControlToValidate="rblstTest" 
                                OnServerValidate="testSeverValidation" 
                                ClientValidationFunction="testClientValidation" 
                                Display="Dynamic" 
                                ErrorMessage="Error!" runat="server"/&gt;

 &lt;asp:LinkButton runat="server" ID="lnkSubmit" Text="Submit"  /&gt;
 &lt;/div&gt;  
 &lt;/asp:Content&gt;
</code></pre>
