Work orders completed but no "completed" dollars - costs all go to variance accounts

 Occasionally we have a work order complete with incorrect manufacturing accounting.  The standard and actual costs are correct, but the completed costs do not process and the A1, B1, C4, etc. costs all post to variance accounts.  The item ledger looks correct, but we believe the general ledger is off because dollars went to the variance accounts.  What could be causing this to happen?