Creating Excel chart using asp.net c#

protected void btn_download_Click(object sender, EventArgs e)
    {
        from = (fromCalendar.SelectedDate);
        to = (ToCalendar.SelectedDate);
        client_id = Convert.ToInt32(drp_Client.SelectedValue);
        Compaign = drp_Compaign.SelectedValue;
        
        try
        {

            SqlCommand cmd_down_tw = new SqlCommand("proc_GetSemDataFromToDate", con);
            cmd_down_tw.CommandType = CommandType.StoredProcedure;

            cmd_down_tw.Parameters.Add("@FromDate", System.Data.SqlDbType.DateTime).Value = (from);
            cmd_down_tw.Parameters.Add("@ToDate", System.Data.SqlDbType.DateTime).Value = (to);
            cmd_down_tw.Parameters.Add("@ClientId", System.Data.SqlDbType.Int).Value = (client_id);
            cmd_down_tw.Parameters.Add("@Compaign", System.Data.SqlDbType.VarChar).Value = (Compaign);

            SqlDataAdapter da_down_tw = new SqlDataAdapter(cmd_down_tw);
            da_down_tw.SelectCommand = cmd_down_tw;
            DataTable dt_down_tw = new DataTable();
            da_down_tw.Fill(dt_down_tw);

            SqlCommand cmd_comp_tw = new SqlCommand("proc_GetAllSemDataFromToDate", con);
            cmd_comp_tw.CommandType = CommandType.StoredProcedure;

            cmd_comp_tw.Parameters.Add("@FromDate", System.Data.SqlDbType.DateTime).Value = (from);
            cmd_comp_tw.Parameters.Add("@ToDate", System.Data.SqlDbType.DateTime).Value = (to);
            cmd_comp_tw.Parameters.Add("@ClientId", System.Data.SqlDbType.Int).Value = (client_id);
            cmd_comp_tw.Parameters.Add("@Compaign", System.Data.SqlDbType.VarChar).Value = (Compaign);

            da_comp_tw = new SqlDataAdapter(cmd_comp_tw);
            da_comp_tw.SelectCommand = cmd_comp_tw;
            dt_comp_tw = new DataTable();
            da_comp_tw.Fill(dt_comp_tw);

            dt_down_tw.Merge(dt_comp_tw);

            //DataTable[] data_tables = new DataTable[2];
            //data_tables[0] = dt_comp_tw;
            //data_tables[1] = dt_down_tw;

            ExportDataSetToExcel(dt_down_tw, "Report.xls");
            dt_down_tw.Dispose();            
        }
        catch
        {

        }
    }
    public void ExportDataSetToExcel(DataTable dt, string filename)
    {
        HttpResponse response = HttpContext.Current.Response;

        // first let's clean up the response.object   
        response.Clear();
        response.Charset = "";

        // set the response mime type for excel   
        response.ContentType = "application/vnd.ms-excel";
        response.AddHeader("Content-Disposition", "attachment;filename=\"" + filename + "\"");

        // create a string writer   
        using (StringWriter sw = new StringWriter())
        {
            using (HtmlTextWriter htw = new HtmlTextWriter(sw))
            {
                // instantiate a datagrid   
                DataGrid dg = new DataGrid();
                dg.DataSource = dt;

                dg.DataBind();
                dg.RenderControl(htw);
                response.Write(sw.ToString());
                response.End();
            }
        }
    }