Purchase order Workflow

Hi

I'm using standard workflow WS20000075 for Purchase order approvals.

The workflow gets de-activated after every run .

I checked the log and it's complianing about all parameters not received.

I checked and found that the purchase order number was sent but the release code is blank .

How do I get the release code into the WF ?Is it something that needs to be done on the release startegies?

Many thanks

Gerhard