This document explains the error AccountIdNull when converting from Order to BILL in MYOB.
Error message as below when doing a conversion in MYOB, which is an MYOB known issue.
2. If getting error below'AccountID NULL' in MYOB while converting, this is a myob bug and need to tick all items as:-
3. Assign account to EXPENSE and INCOME - set TAX CODE.
4.. Convert to BILL.
5. Please set up all new items as I BUY ISELL I INVENTORY to avoid this issue in future.