Set Focus to textbox after updatepanel updates

VB.NET

I have a gridview in a update panel displaying a set of records. When I select a record I want to set focus to a text box. This following script will do that

Set the following cod under the script manager or you will get the sys object not found error

<script type="text/javascript" language="javascript">
    Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);
    function EndRequestHandler(sender, args) {
        //Use timer so that the script will wait .5 sec before it fires to let page complete rendering the txtDSChartNumber element
       setTimeout ( 'setFocus(\'txtDSChartNumber\')', 500 );
     }
     function setFocus(controlid) {
        if (document.getElementById(controlid)){
            document.getElementById(controlid).focus();
            document.getElementById(controlid).select();
         }
     }
</script>