Gift cards can struggle as they do tend to produce an unknown as a response instead of yes for zip code matching and street number matching causing the transaction attempt to decline. There is a way around this with most gift cards. If the donor looks on the back of the card, there is likely a website they can go to where they can check their balance. Often there will also be a place where they can enter their name and address on that website. If they do this, the response should become yes instead of unknown allowing the transaction to go through.