Declined 76561198003704323 (BigBro)

Victim:
|steamID: raff
|steamID32: STEAM_0:1:40209774
|steamID64: http://steamcommunity.com/profiles/76561198040685277
|customURL: http://steamcommunity.com/id/raff_/
|steamrepURL: http://steamrep.com/profiles/76561198040685277

Scammer:
|steamID: BigBro
|steamID32: STEAM_0:1:21719297
|steamID64: http://steamcommunity.com/profiles/76561198003704323
|customURL: http://steamcommunity.com/id/yo_
|steamrepURL: http://steamrep.com/profiles/76561198003704323

Screenshot:
http://imgur.com/mGfre

Description: BigBro had created a trade on tf2outpost saying that he is selling a treasure hat for 10 keys+wrap. So i added him and made an offer of 7 eerie keys and wrap and he accepted. At first I told him that I would need some sort of collateral to make sure he's not scamming and I would give it back in the final trade. He didn't seem like an experienced trader so I eventually caved in and just traded it without collateral. Directly after the trade he said "BigBro: wait 5 min BigBro: " After that I questioned him and waited the 5 minutes with no response. Then he deleted me from friends. I really hope something is done to prevent this from happening for it seems like it happens quite often.

Please provide a picture of your inventory history , in which you are trading him the keys.
( Go To your steam profile > Click Inventory > Right Under Gifts , Click "View Inventory History" > Then Scroll Down , Until you see the trade )

We need this information.

Requested Evidence was not supplied -- feel free to submit a new report if you have the evidence.