exporting gridview data in excel on button clicked

public void exportRequest()
{
Response.ClearContent();
Response.Buffer = true;
Response.AddHeader("content-disposition", string.Format("attachment; filename={0}", "Work Schedule.xls"));
Response.ContentType = "application/ms-excel";
StringWriter sw = new StringWriter();
HtmlTextWriter htw = new HtmlTextWriter(sw);

grdvwOverdueWorkOrders.AllowPaging = false;
grdvwOverdueWorkOrders.AllowSorting = false;
//grdvwOverdueWorkOrders.DataBind();
BindGridview();
grdvwOverdueWorkOrders.Columns[0].Visible = false;
grdvwOverdueWorkOrders.Columns[3].Visible = false;
grdvwOverdueWorkOrders.Columns[1].ItemStyle.Width = 150;
grdvwOverdueWorkOrders.Columns[2].ItemStyle.Width = 150;
grdvwOverdueWorkOrders.Columns[5].ItemStyle.Width = 150;
grdvwOverdueWorkOrders.Columns[6].ItemStyle.Width = 100;
grdvwOverdueWorkOrders.Columns[7].ItemStyle.Width = 100;
grdvwOverdueWorkOrders.Columns[8].ItemStyle.Width = 100;

grdvwOverdueWorkOrders.Columns[9].ItemStyle.Width = 100;
grdvwOverdueWorkOrders.Columns[10].ItemStyle.Width = 150;
grdvwOverdueWorkOrders.Columns[12].ItemStyle.Width = 150;
grdvwOverdueWorkOrders.Columns[14].ItemStyle.Width = 150;
grdvwOverdueWorkOrders.Columns[16].ItemStyle.Width = 150;
//Change the Header Row back to white color
grdvwOverdueWorkOrders.HeaderRow.Style.Add("background-color", "#FFFFFF");
//Applying stlye to gridview header cells
for (int i = 0; i < grdvwOverdueWorkOrders.HeaderRow.Cells.Count; i++)
{
grdvwOverdueWorkOrders.HeaderRow.Cells[i].Style.Add("background-color", "#df5015");
}
grdvwOverdueWorkOrders.RenderControl(htw);
Response.Write(sw.ToString());
Response.End();



}

I have 1000 records but when I exporting to excel .I am getting error. I am not able to read the records in excel sheet after exported gridviewdata

plz help me