public override void buttonAdd_Click(object sender, EventArgs e)
        {
            MainClass.Enable_Reset(panelRightSlider);
            comboBoxSelectProduct.Enabled = false;
            textBoxQuantity.Enabled       = false;
            textBoxTotalCost.Enabled      = false;
            textBoxProdCost.Enabled       = false;
            textBoxPONumber.Enabled       = false;
            textBoxUnit.Enabled           = false;
            DataTable dt = new DataTable();

            //      dt = retrieve.GetId("usp_GetPOID", comboBoxSelectProduct.Text);
            //PoNumber = Convert.ToInt32(dt.Rows[0][0].ToString()) + 1;
            //textBoxPONumber.Text = PoNumber.ToString();
            textBoxPONumber.Text = retrieve.RetrunPoNumber().ToString();
        }