We cannot post the billing document to accounting due to the error "Message no. F5611 - Acct determination for Tax exchange rate differences with keys not defined in ch/acts xxxx". Checked and verified d that there are no settings in OBYC for the Company Code . Further there are identical Sales Orders / Deliveries and Billing docs created previously without this issue. They were posted to Accounting successfully. What could be the possible reason. Thank you in advance.