Hi Yanmtl,

My suggestion is to do a manual bank rec and see if you can make the book side and the bank side balance

You can print the General Ledger report of the bank account as of the month you are working for your bank rec.  Then, you put it side by side with your monthly bank statement.  Cross out item that both appear in the report and the bank statement.  Then, you should be able to figure out what you are missing. 

If you still unable to figure out what the unresolved amount is, you can create a backup by going to File, Backup.  Then, you can follow the link at the end of the article - My Bank reconciliation has a discrepancy and/or an unresolved amount and reset your bank reconciliation.

Hope this helps.