FM workflow is restarting

Hi.

I have implemented a workflow for funds reservartion approval (it's a copy of standard workflow WS50000016) with triggering events FMRE-CREATED and FMRE-CHANGED. Approval procedure is working fine when document is created (transaction FMX1) or changed (transaction FMX2).

A funds reservation document has a Purchase Requisition as subsequent document. Problem is: when PR is modified (transaction ME52N) system triggers again the event FMRE-CHANGED and funds reservartion document goes to approval procedure again. This is in production system; QAS works fine.

Any idea in how to evoid this behavior? Thanks for any help.

Kind regards.

Juan