AP/AR Netting error

Why is a completed AR Invoice not retreived by a Netting Batch?  Are there additional setups, config steps. The AP Invoice and the AR Invoice are 'booked/recorded' with the AP Supplier & AP Customer that is setup in the Netting Agreement ... The AP Invoice is properly retrieved ...

Error message #1:

**Starts**08-MAY-2013 15:59:27

**Ends**08-MAY-2013 15:59:27

+---------------------------------------------------------------------------+

Start of log messages from FND_FILE

+---------------------------------------------------------------------------+

No transactions were selected for netting since there were no outstanding balances in AP and AR.

+---------------------------------------------------------------------------+

End of log messages from FND_FILE

+---------------------------------------------------------------------------+

Error message #2:

Output file size: 0 +------------- 1) PRINT   -------------+Disabling requested Output Post Processing.  Nothing to process.  The output of the request is zero byte.+--------------------------------------+