Include shipping cost before coupon is applied

I tried to create a gift card. I did a test with discounts but it never works, I tried with coupons and it works. Now I have two problems. First, really important for me, it's the shipping isn't included in the total before applying the discount with the coupon code. I tried to edit /administrator/components/com_hikashop/classes/discount.php trying to change the calculation but never mind if I delete this file, nothing happen. Have somebody any idea to how I can solve this? Thank you so much

Hello,

I'm sorry but it's not possible to understand your message. Are you sure that you want to post in HikaSerial ?!
But the only thing I can tell you is : Do not edit HikaShop core files.

Regards,