HOw to put condition statement for the following ASp.NET 2.0
<p>I have the following code in the front end</p>

<pre><code> &lt;asp:Content ID="Content1" ContentPlaceHolderID="cphMain" runat="server"&gt;
        &lt;script type="text/javascript"&gt;
            //on upload button click temporarily disables ajax to perform upload actions
            function conditionalPostback(sender, args) 
            {
                if (args.EventTarget == '&lt;%= ((Button)frmvwMainDetail.FindControl("bttnRateUploadUpload")).UniqueID %&gt;') {
                    args.EnableAjax = false;
                }
            }
        &lt;/script&gt;
    ...
&lt;/asp:content&gt;
</code></pre>

<p>When the page load, it' complaining about ((Button)frmvwMainDetail.FindControl("bttnRateUploadUpload")).UniqueID is null value. So my question how to put some checking on this ?</p>
