I assure you, there is no link displayed for this giveaway. See screenshot: http://imgur.com/GvfybtN

I also notice that your other giveaway from the same day also was never marked as received, perhaps for the same reason. When you go to your "created" giveaways page at https://www.steamgifts.com/giveaways/created do you see a link in the "keys" column? If you're not seeing a link there, then the key or link was never attached. If you see a link, then there's some sort of bug with the giveaway.