Purchase Order Dispatch - Meaning of message

During PO Dispatch we are getting the following message

"Purchase Order, BU001 / 0000099999,  has been Dispatched.  Please detach and print the attached Purchase Order. Found BU001 purchase orders which are not included in the rollover process"

where BU001 is our business unit.  Can anyone tell me the meaning of the "found purchase orders which are not include in the rollover process" part of this message?   I tried to search for it, but didn't come up with anything.

Thanks in advance.

Please move this to a more appropriate community if this isn't where it belongs.  I didn't see any communities for Purchasing, ePro, Vendors, etc.