Backend error message when changing old PO's in upgraded system

Hi,

We upgraded our SRM system from 5 to 7.1

The issue we are facing is that fir all OLD PO's in the system,which were created before the upgrade,if we change the price or delete service lines in PO,then an error message is displayed "Backend error:Purcahse ordre still contains faulty items".

Has anybody come across this issue?

NOTE: This happens only for old PO's in the system.