Josh,
If you are using Workflow to Approve the prepayment, after it is approved you can Create Prepayment Invoice. Did the AP person Send the Purchase Order for Approval first or click Create Prepayment Invoice? If the latter, if the Prepayment Invoice, is approved, the User can Post the Prepayment Invoice. Then you can create the Payment Journal to Pay the Prepayment Invoice. After you make the Payment, the Purchase Order Status will update to Released, since the pending prepayment was paid.
Also, make sure on Purchase & Payables setup page you set the field Check Prepmt. when Posting = TRUE
Hope this helps.
Thanks,
Steve
