magento 1.9 – setDiscountAmount not working

I’m programatically setting a discount on my checkout.

I am able to change my grandTotal and subtotal just fine, the problem is with the Discount Amount, it doesnt’t matter what I do, the discount message/value won’t appear. Any clue on what I am doing wrong?

    $totalDiscount = floatval($pixDiscount) * floatval($address->getSubtotal()) / 100;

        

        $address->setSubtotal(0);
        $address->setBaseSubtotal(0);

        $address->setSubtotalWithDiscount(0);
        $address->setBaseSubtotalWithDiscount(0);

        $address->setGrandTotal(0);
        $address->setBaseGrandTotal(0);


        $address->setDiscountAmount(0);
        $address->setBaseDiscountAmount(0);


        $address->setGrandTotal($address->getGrandTotal() - $totalDiscount);
        $address->setSubtotal($address->getSubtotal() - $totalDiscount);
        $address->setDiscountAmount($totalDiscount);
        $address->setBaseDiscountAmount($totalDiscount);
  


        $address->save();