in my gridview there is no color in header row but when i am doing expert to excel i want my excel has header color like yellow or somthing else. I have tried all the comment lines in bellow code to do this but still it is not working.Could you help me?

private void ExportGridToExcel(string strFileName, GridView lGridview)
    {
        try
        {
            string Header = string.Empty;
            if (lblmsg.Text != "")
                Header = lblmsg.Text;
            else
                Header = "Unitwise Hotel Report";
            Response.Clear();
            Response.Buffer = true;
            Response.ClearContent();
            Response.ClearHeaders();
            Response.Charset = "";
            string FileName = strFileName.Replace(",", " ").Replace(":", " ").Replace("/", " ") + ".xls";
            StringWriter strwritter = new StringWriter();
            HtmlTextWriter htmltextwrtter = new HtmlTextWriter(strwritter);
            Response.Cache.SetCacheability(HttpCacheability.NoCache);
            Response.ContentType = "application/vnd.ms-excel";
            Response.AddHeader("Content-Disposition", "attachment;filename=" + FileName);

            //grdUnitwiseHtl.HeaderRow.Style.Add("background-color", "Blue");
            //grdUnitwiseHtl.HeaderRow.Style.Add("bgColor", "FF8080");
            //grdUnitwiseHtl.HeaderRow.CssClass = "header";

            //grdUnitwiseHtl.HeaderStyle.BackColor = System.Drawing.Color.DarkBlue;
            //grdUnitwiseHtl.BackColor = System.Drawing.Color.Red;

            //System.Web.UI.HtmlTextWriter htmlWrite = new HtmlTextWriter(strwritter);
            ////Add the control to the forms
            //DataGrid dgRecord = new DataGrid();
            //this.grdUnitwiseHtl.Controls.Add(dgRecord);
            ////Color Setttings
            //grdUnitwiseHtl.HeaderStyle.BackColor = System.Drawing.Color.Blue;           
            ////Cells color settings
            //foreach (DataGridItem dgi in dgRecord.Items)
            //    foreach (TableCell tcGridCells in dgi.Cells)
            //        tcGridCells.Attributes.Add("class", "sborder");
            ////Render the datagrid
            //dgRecord.RenderControl(htmlWrite);

            //for (int col = 0; col < grdUnitwiseHtl.HeaderRow.Controls.Count; col++)
            //{
            //    TableCell tc = grdUnitwiseHtl.HeaderRow.Cells[col];
            //    tc.Style.Add("color", "#FFFFFF");
            //    tc.Style.Add("background-color", "#444");
            //}

            grdUnitwiseHtl.GridLines = GridLines.Both;
            grdUnitwiseHtl.HeaderStyle.Font.Bold = true;
            grdUnitwiseHtl.HeaderStyle.ForeColor = System.Drawing.Color.Yellow;
            grdUnitwiseHtl.HeaderStyle.Wrap = true;
            grdUnitwiseHtl.RowStyle.Wrap = true;
            grdUnitwiseHtl.RenderControl(htmltextwrtter);

            //string s = htmltextwrtter.InnerWriter.ToString();
            //if (s.Contains("<tr class"))
            //{
            //    s = s.Replace("<tr ", "<tr style='font-weight:bold;' bgColor='#FF8080'");

            //}
            //htmltextwrtter.InnerWriter.Write(s); 
            string headerTable = @"<Table bgColor='#FF8080' ><tr><td colspan='3' rowspan='2' ><B><span style='text-align:center'>" + strFileName + "</span></B></td></tr></Table>";
            Response.Write(headerTable);
            Response.Write(strwritter.ToString());
            Response.End();
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }