How to get ASP.Net gridview in master page which is placed in ContentPlaceHolder

Looking to have a export button in master page. Gridview is placed inside panel, so I couldn't get the gridview to export to excel. I have gridview's wherein I can able to export to excel that are directly placed in maincontent(Content PlaceHolder). The problem is if gridview is placed inside panel I couldn't export.

 protected void LinkButtonExport_Click(object sender, EventArgs e)        {
            foreach (Control ctr in MainContent.Controls)            {
                GridView gv = ctr as GridView;                if (gv != null)
                {                    ExportUtil.Export("Test.xls", gv);
                }                else                {
                    LinkButtonExport.Enabled = false;                }
            }}