Fix Header Gridview mounting scroll on top

I use function for mounting scroll on top gridview.

function Freeze_Div(divFreeze) {
    // This Script is used to maintain Grid Scroll on Partial Postback
    var scrollTop;
    //Register Begin Request and End Request
    Sys.WebForms.PageRequestManager.getInstance().add_beginRequest(BeginRequestHandler);

    Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);
    //Get The Div Scroll Position

    function BeginRequestHandler(sender, args) {
        var m = document.getElementById(divFreeze);
        scrollTop = m.scrollTop;

    }
    //Set The Div Scroll Position
    function EndRequestHandler(sender, args) {
        var m = document.getElementById(divFreeze);
        m.scrollTop = scrollTop;

    }

}

now when used a  ScrollableGridViewPlugin_ASP.NetAJAXmin.js for fix header gridview the function Freeze_Div not work. tanks for any help.