vmError: 81128: AuthorizationID : Required parameter missing

[ProRaceSupply]

When we try and refund an order from within VM admin (checkout via Paypal payments pro) , we get the error message back "vmError: 81128: AuthorizationID : Required parameter missing"

Payment authorization and capture work just fine.  WHen you try an refund - no dice.  You have to go into paypal and cancel manually.

Joomla 2.5.28
Virtuemart 2.16.17 (Though this also happened in all previous versions.)

Thanks for any help.