Parked invoice document attachment not updated automatically

Hello

We are in process of chnaging the mass parked MM invoice documents to new year 2015 posting data at a time.

with the help of scn forums, we got BAPI (BAPI_INCOMINGINVOICE_CHANGE) and we posted new posting date in 2015 yr folr the old parked couemnt of year 2014 &2013 yr.

Now the for the old parked documents attachment were available. for these old parked documents, new parked document created in the Jan 2015 yr wth new posting date with above BAPI.but the attachments are not updated automatically in the new parked invoice documents. why?

what could be the reason, why the attachments are note updated. any clue!!!

Regards

Pabbati Obulesu