Invalid Missing item after trading


Hi, I had a trade with another player at July 05 (16ees for 800cs, around 11:30~12:00?, I can't remember the exactly time)
* at 1st try, the trade fail because my use inventory was full.
* at 2nd try, I put 16ees in but the other guy said he need to afk abit. After I wait about 1 or 2 mins (I can't remember the exactly time), he put 800cs in and the trade went smoothly.
I log to my other char and went on with the game but he messaged me said he only got 1ees.
I log back to the old char to check. There's only 1ees left in my inventory (I had 17ees before the trade) so that means there're 15ees missing in the trade.

We tried contact a gm and he said we should report the bug here.
I hope we can get back the missing item.
Thank you guys for all your help.

My trading char IGN is lilgirl.