Unable to use the Purchase Organisation

Hi,

I created a Purchase Organisation("DPO") at Company Code level (not at plant"DGP" level).

During maintain source list i enter my pur org name "DPO" I get the error message "PURCHASING ORGANISATION DPO NOT RESPONSIBLE FOR PLANT DGP"

Is there anyway to use the same purchase organisation at plant level & company code level? Basically I want to use this Purchase Organisation for my Plant DGP.

Thanks

R Auluck