Account required an assignment to co object

Dear All,

The issue is key user has created the invoice and against this invoice document created the excise invoice.

On checking with the balances with customers account,we found that , this invoice is not been posted to accounting.In VF02 tried to save this document,It is giving the massage Document saved and no accounting document generated.I have checked the revenue account determination analysis,it is showing the correct GL`s.When I tried to release this document to accounting,error is Account required -

a assignment to co object.Where as, to this GL before and after this document postings happened.In material master the profit center is maintained.

The keyuser got the massage during PGI regarding the co object not assigned.So he maintained the profit center in the material.After this he has created the Invoice.

How to release this document to accounting.

deepti