Invoice being created in the wrong depreciation book during Mass Additions Create

Hello -

We have one Ledger with 5 operating units and 5 corporate depreication books.  We are running into an issue were invoices are being created on the wrong depreciation book.  Our question is in this type of setup, how does AP know what invoices shoudl be created on what depreciation book?  We are not entering the Asset Book onthe invoice but want company 110 only in depreciation book A, 210 on depreciation book B, nad 310 on depreciation book C.  We are seeing 310 on all depreciation books.

Any suggestions would be greatly appreciated.