1.5 Bug in the ApplyDiscountCouponCode() method

protected void ApplyDiscountCouponCode()
        {
            string couponCode = this.txtDiscountCouponCode.Text.Trim();
            if (String.IsNullOrEmpty(couponCode))
                return;

            bool isDiscountValid = true;
            if (isDiscountValid)
            {
                pnlDiscountWarnings.Visible = false;
                lblDiscountWarning.Visible = false;

                CustomerManager.ApplyDiscountCouponCode(couponCode);
                this.BindData();
            }
            else
            {
                pnlDiscountWarnings.Visible = true;
                lblDiscountWarning.Visible = true;
                lblDiscountWarning.Text = GetLocaleResourceString("ShoppingCart.DiscountCouponCode.WrongDiscount");
            }
        }