This forum is to discuss different features/issues of Oracle Financials modules ( GL - General Ledger, AP - Accounts Payable, AR - Accounts Receivable, FA - Fixed Assets & CM - Cash Management ).
I think you are Enabled check Box Budgetary Control In the defining SOB .thats why Post Button is disabled and two buttons (Check Funds,Reserve Funds)Enabled.
With the above possibilities , Check the any work flow using. If so, Posting option might not be available to you and that option might be with your next position.