[Solved] ASP.Net ClosedXML error: Cannot find table 1

Solved.

    protected void BtnExcel_Click(object sender, EventArgs e)
    {
        try
        {
            str = " SELECT DISTINCT ROUTE_CODE FROM CT_CUSTOMER_MIS WHERE DIV_CODE='" + Session["DivCode"].ToString() + "' AND BRANCH_CODE='" + ddlBranchCode.SelectedValue + "' " +
                  " AND CUSTOMER_CODE='" + ddlCustomer.SelectedValue.Split('>')[0].ToString().Trim() + "'  ORDER BY ROUTE_CODE ";     
            DataSet ds = oper.DTSET(str);
            XLWorkbook wb = new XLWorkbook();
            for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
            {
                string SheetName = ds.Tables[0].Rows[i][0].ToString();
                //ds.Tables[i].TableName = SheetName;
               
                
                string str2 = " SELECT SR_NO,ROUTE_CODE,ROUTE_DESC,INVOICE_NO,TO_CHAR(INVOICE_DATE,'dd-Mon-yyyy')INVOICE_DATE,DISPATCH_DATE,PICKUP_CODE,DELIVERY_CODE,DEALER_CODE, " +
                      " REGIS_NO,FLEET_TYPE,DSL_FLG,DSL_AMNT,QNTY,MNF_NUMBER,HSN_CODE,NVL(RATE,0)RATE,NVL(TOTAL,0)TOTAL FROM CT_CUSTOMER_MIS WHERE DIV_CODE='" + Session["DivCode"].ToString() + "' AND BRANCH_CODE='" + ddlBranchCode.SelectedValue + "' " +
                      " AND CUSTOMER_CODE='" + ddlCustomer.SelectedValue.Split('>')[0].ToString().Trim() + "'  AND ROUTE_CODE='" + ds.Tables[0].Rows[i][0].ToString() + "'  ORDER BY SR_NO "; 
                br = oper.DTSET(str2);
                for (int k = 0; k < br.Tables.Count; k++)
                {
                    wb.Worksheets.Add(br.Tables[k], SheetName);
                }
            }
            Response.Clear();
            Response.Buffer = true;
            Response.Charset = "";
            Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
            Response.AddHeader("content-disposition", "attachment;filename=ddlCustomer.SelectedValue.Split('>')[1].ToString().Trim().xlsx");
            using (MemoryStream MyMemoryStream = new MemoryStream())
            {
                wb.SaveAs(MyMemoryStream);
                MyMemoryStream.WriteTo(Response.OutputStream);
                Response.Flush();
                Response.End();
            }
        }
        catch (Exception ex)
        {
            string s = ex.Message;
            s = s.Replace("\"", "");
            s = s.Replace("'", "");
            s = s.Replace("\r", "\\r");
            s = s.Replace("\n", "\\n");
            ScriptManager.RegisterStartupScript(this, typeof(Page), "Error", "<script>showpop6('" + s + "')</script>", false);
        }
    }