I have Timeslips 2011

I have run and approved all bills this month.  There are no further bills showing in proof or revision stage. However, there is one bill that is not on the "undoable" list and is showing elsewhere as still in proof stage.  I can reprint it but there is nothing else I can do with it. For example, when I go into accounts receivable, there is no balance or receivables showing.

I ran an error and data verification.  I get an error that says that this client is on a bill that is currently being approved.  You cannot edit this record until the bill approval process is complete.  

But, I cannot approve it because it is not the list for bills in proof or revision stage.

Help!  How do I approve this bill?