Small amount was working... then tried bigger transfer ==> FAILED 
Check your transactionid in the explorer.
https://chainz.cryptoid.info/eac/
Transaction is confirmed on blockchain... but not credited!!!
Maybe it is very busy with EAC deposits/withdrawals now, just wait for a while.
Otherwise you have prove in the blockchain you have send the EAC and that it is present on their deposit adres, then you can contact AEX support.