Error When Posting Returns Delivery

Hello Everyone,

I am encountering an error in SAP whenever I am trying to post a returns delivery - "Value of Goods Movement is Negative".

I checked OMJJ and negative posting for 122 is allowed. Is there an explanation for this? How can I compute the value of the 122 and where is it coming from?

Other details

1. The material I try to return's PO price is 482.81 per 1000 kg.

2. I post GR with quantity 35, 710 kg with value USD 17, 241.15 on 1/15/2010

3. Invoiced on 1/19/2010 wuth 35,710 kg with value USD 16, 896.33

Thanks in advance!