[Solved] Exporting multiple ASP.Net GridView to Excel file is blank (empty)

Export Multiple GridView data into excel but GridView is not getting exported

EXCEL FILE DOWNLOADING EMPTY

 I follow your below reference 

Exporting Multiple GridViews To Excel SpreadSheet in ASP.Net

protected void LinkButton1_Click(object sender, EventArgs e)
{
    Response.Clear();
    Response.Buffer = true;
    Response.AddHeader("content-disposition",
        "attachment;filename=GridViewExport.xls");
    Response.Charset = "";
    Response.ContentType = "application/vnd.ms-excel";
    StringWriter sw = new StringWriter();
    HtmlTextWriter hw = new HtmlTextWriter(sw);
    PrepareForExport(GVdaily);
    PrepareForExport(GVManual);
    Table tb = new Table();
    TableRow tr1 = new TableRow();
    TableCell cell1 = new TableCell();
    cell1.Controls.Add(GVdaily);
    tr1.Cells.Add(cell1);
    TableCell cell3 = new TableCell();
    cell3.Controls.Add(GVManual);
    TableCell cell2 = new TableCell();
    cell2.Text = " ";
    if (rbPreference.SelectedValue == "2")
    {
        tr1.Cells.Add(cell2);
        tr1.Cells.Add(cell3);
        tb.Rows.Add(tr1);
    }
    else
    {
        TableRow tr2 = new TableRow();
        tr2.Cells.Add(cell2);
        TableRow tr3 = new TableRow();
        tr3.Cells.Add(cell3);
        tb.Rows.Add(tr1);
        tb.Rows.Add(tr2);
        tb.Rows.Add(tr3);
    }

    tb.RenderControl(hw);
    //style to format numbers to string
    string style = @"<style> .textmode { mso-number-format:\@; } </style>";
    Response.Write(style);
    Response.Output.Write(sw.ToString());
    Response.Flush();
    Response.End();
}

private void PrepareForExport(GridView Gridview)
{
    Gridview.AllowPaging = Convert.ToBoolean(rbPaging.SelectedItem.Value);
    Gridview.DataBind();
    //Change the Header Row back to white color
    Gridview.HeaderRow.Style.Add("background-color", "#FFFFFF");
    //Apply style to Individual Cells
    for (int k = 0; k < Gridview.HeaderRow.Cells.Count; k++)
    {
        Gridview.HeaderRow.Cells[k].Style.Add("background-color", "green");
    }

    for (int i = 0; i < Gridview.Rows.Count; i++)
    {
        GridViewRow row = Gridview.Rows[i];
        //Change Color back to white
        row.BackColor = System.Drawing.Color.White;
        //Apply text style to each Row
        row.Attributes.Add("class", "textmode");
        //Apply style to Individual Cells of Alternating Row
        if (i % 2 != 0)
        {
            for (int j = 0; j < Gridview.Rows[i].Cells.Count; j++)
            {
                row.Cells[j].Style.Add("background-color", "#C2D69B");
            }
        }
    }
}