System remove the bank account and put the invoice in document hold

Hell,

Whenever there is change in payment term,system is removing the bank account and put the invoice in hold 'Document Payee Bank Account Number is required'.So we need to remove this hold and relink the invoice.Can't the system auto populate the bank account whenever there is change in payment term?is that the normal process?How to over come it?

Regards,

Dasharath