Error Message : BA could not be created: BP in open item accounting is FI-AR and is FI-CA in IMG

HI CRM Expert,

I have activated business agreement in IMG CRM>Master Data>Business Partner>Busines Agreement>Basic Setting>FI-CA Active

and the function of business agreement activated correctly right now for new business partner that has been created after its activation. but i found problem with my old business partner which had FI-AR active, when i create sales order and asked to create business agreement for this business partner, error message appear like this,

" BA could not be created:BP in open item accounting is FI-AR and is FI-CA in IMG"