ASP.NET modal popup return value

I have an aspx page and inside this page I have FormView. I create ModalPopup using ModalPopupExtender, and inside this form view I have a button and on the Click event I open modal and everything work's fine. But I have on开发者_如何转开发e problem. I try to return value from this modal on the main page to update a Label with the new value. The modal pop-up is in user control.

try as follows ................

    <asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">

       <script language="javascript" type="text/javascript">

               function functioname()

              {

                    document.getElementById("<%=ddlInfo.ClientID%>").value ="123"; 

                  //  or 



 document.getElementById("<%=another panel control.ClientID%">).value = document.getElementById("<%=  selectedPanelcontrol.ClientID%">).value ;  

              }

       </script>

and do vist this for more details http://msdn.microsoft.com/en-us/magazine/cc164247.aspx