private void UpdatePOSelection()
        {
            var allPOsList        = (List <usp_GetPurchaseOrderList_Result>)ObjectDataSourcePOs.Select();
            var selectedPONumbers = PurchaseOrdersGrid.GetSelectedFieldValues(PurchaseOrdersGrid.KeyFieldName);

            _selectedPOs.Clear();
            _selectedPOs.AddRange(allPOsList.Where(p => selectedPONumbers.Any(sp => (int)sp == p.PurchaseOrderNumber)).ToList());
            //SelectedPurchaseOrdersGrid.DataSource = _selectedPOs;
            //SelectedPurchaseOrdersGrid.DataBind();
        }
        protected void PurchaseOrdersGrid_OnSelectionChanged(object sender, EventArgs e)
        {
            return;

            var allPOsList        = (List <usp_GetPurchaseOrderList_Result>)ObjectDataSourcePOs.Select();
            var selectedPONumbers = PurchaseOrdersGrid.GetSelectedFieldValues(PurchaseOrdersGrid.KeyFieldName);

            _selectedPOs = allPOsList.Where(p => selectedPONumbers.Any(sp => (int)sp == p.PurchaseOrderNumber)).ToList();
            //foreach (var selectedPONumber in PurchaseOrdersGrid.GetSelectedFieldValues(PurchaseOrdersGrid.KeyFieldName))
            //{

            //    //var selectedPO = PurchaseOrdersGrid.GetRow(PurchaseOrdersGrid.Get);

            //}
            //var x = PurchaseOrdersGrid.Selection.Count;
            //SelectedPurcaseOrderCount.Text = x.ToString();

            SelectedPurchaseOrdersGrid.DataSource = _selectedPOs;
        }