Lately i've been looking to trade some keys for a cs go knife. So this guy (which i dont have the profile) added me and told he me wanted 38 keys for his flip web. So i said ok, invited him to trade and put all the keys, he put the knife and i clicked make trade. Steam gave me an error and the guy deleted me right after. I didnt lose any items but when i checked his backpack he did not have the knife in it. Today, it happened me again. This guy (http://steamcommunity.com/profiles/76561198042208264/) Offered me 40 keys for his gut night. Accepted the trade and it gave me an error and deleted me right after. I still did not lose any items. Im unaware if they tried to do this for any other game. Sorry if its already known, or if its just a concidence.