Hi
Check whether open PO commitments are created for those POs (FMN4). if FM derivation rules are to be change in new fiscal year 2013 then reassignment strategy will be useful, other wise not required. Seems you are already maintained closing operations all settings. Check it once again settings and value types maintained. Are you using yearly budget or overall budget?
If you execute open PO commitments already, you will receive the same message saying that no open items exit.. check the reports also.
Regards
Rao
