0% received by users

I had the very same problem and got unbanned after we talked it all over. If it's an honest mistake, just get another key for the winner; as long as people are reasonable, there should be no problem. Make sure you're not getting scammed, though... "Oh no, this key ALSO did not work! Whatever shall we do! Can I have another key?" ;)

then he won't have to worry about rating anyway

Steam has done that to me on every single gift I've ever received or sent. It's annoying, being told always that things are invalid, but they still go through most times.

nope was not added