Не выводит скидку, $order->getDiscountPrice()

 function getDiscount($order)
 {
        $discount = 0;
        $basket = $order->getBasket();
        
        foreach ($basket as $item) {
            $discount += ($item->getBasePrice() - $item->getPrice()) * $item->getQuantity();
        }
        
        return $discount;
 }