Hello, please, provide your contest account number and the ticket of the trade you can't close.
What error do you see when you are unable to close?

Was it 'trade context busy' by any chance?
The error message “trade context is busy” is displayed when the client is trying to open/close/modify several orders at the same time.
Any operation (opening/closing or modifying an order) is actually a request (command) sent to the trading server via the terminal Meta Trader 4. Meta Trader 4 is programmed in a way, that does not allow to send several requests (commands) at the same time. You have to wait before one request is executed, then make the next request. If you make the second command and the first command has not been completed, you will get the error #146: 'trade context is busy' and the second request will fail.
This often happens when you have several EAs enabled on different charts (or timeframes) and 2 or more EAs are trying to open/close/modify a trade at the same time.
This is an issue with the Meta Trader Terminal, and it is not related to FXOpen trading terms and conditions or any problems with FXOpen trading servers. Please, refer to http://articles.mql4.com/141

hi, do you see any error messages? What is the ticket of the trade?

well, i dont use ea, only custom indicators. In fact it happened to me few times again on my EU just now. I noticed it only happens during major move. Oh well, no point in rectifying anything. My account is totally wiped now. Guess im out of the game now. Good luck to everyone else.