Getting data in Model popup extender

I have shown modelpopupExtender on mouse over event on gridview linkedbutton named as (lnkclientName)
protected void GV_Main_RowDataBound(object sender, GridViewRowEventArgs e) {
Label lbl_ClientID = (Label)e.Row.FindControl("lblClientID");
LinkButton lnkCName = (LinkButton)e.Row.FindControl("lnkClientName");
if (lnkCName != null && lbl_ClientID != null) {
lnkCName.Attributes.Add("OnMouseOver", "javascript:MouseHover()"); }
----aspx file
<script type="text/javascript" language="javascript"> function MouseHover() { $find("modelPopupExtender1").show(); } </script>

}
<aj:ModalPopupExtender runat="server" BehaviorID="modelPopupExtender1" TargetControlID="HyperLink1" PopupControlID="popUpPanel" BackgroundCssClass=&qu ...