How to prevent that users can not to do a Return to Supplier if the PO is invoiced.

Hi everyone,

Someone can help me with any alternative or solution in order to prevent that users can not to do any return to supplier if the PO is invoiced. For error when a PO is received and invoiced, the users enter Return to Supplier without see that PO have one or many invoices related. I need that the application not allow at users to make a transaction "Return to Supplier" if the PO's had invoices.

Thanks for the support at this discussion.

Carlos