Invalid ? (?)

Victim
steamID: Ricardo romano
steamID32: STEAM_0:0:41526090
steamID64: http://steamcommunity.com/profiles/76561198043317908
customURL:
steamrepURL: http://steamrep.com/profiles/76561198043317908

Scammer
steamID: Expired Milk
steamID32: STEAM_0:1:43861257
steamID64: http://steamcommunity.com/profiles/76561198047988243
customURL: http://steamcommunity.com/id/LoS_Raza
steamrepURL: http://steamrep.com/profiles/76561198047988243

Screenshots
http://imgur.com/U33Lh
http://imgur.com/kZV62
http://imgur.com/aMrfB
http://imgur.com/Wh9GO
a guy came up and said how much for my balloonicorn at first i told him not for sale and closed the chat then he said it again i decided to sell it i check spreadsheet i was dumb enough to believe that when spreadsheet said
2-/+ it would say ref or key and the guy offered the planeswalker so because of spreadsheet i thought 2-\+ was 2 keys and when he offered planeswalker i thought then after the trade he said to this guy that he got me the guy copied and pasted it to chat and i copied and paste it to him then he kept saying you scammed me you scammed me give me my stuff back i got kinda mad and please mark this guy as a scammer and i have no problem giving the hat back for the misc i really dont i dont like scamming or scammers so help me out i never got approved so i hope this one does

can i have a reason why it was marked ?(?)