protected void btnDiscount_Click(object sender, EventArgs e) { if (BusinessLogic.CheckPromoCode(txtDiscount.Text)) { pnlPromoCode.Visible = true; lblPromoCode.Text = "Discount Code Applied!"; Session["promoCode"] = txtDiscount.Text; } else { pnlPromoCode.Visible = true; lblPromoCode.Text = "Invalid Code!"; } }