P04423 Open AP Detail by Supplier report shows a document without an original amount (gross) but the

<Q> P04423 Open AP Detail by Supplier report shows a document without an original amount (gross) but the open amount is populated with a credit amount on specific As of date. What could be the cause of this?

<A>  This is regarded as a prepayment. So, the gross amount is blank, because the invoice does not exist.  The amount for the payment needs to be shown and that is in the open amount as a positive amount, because the invoice was a credit. You might see if you can set processing options for prepayment processing on P04423 to a value of 1 to see if this will help balance on the as of report.