T-code: VF01 is to create billing document.
1. Create Invoice.
1) Input Sales Order no. and execute it.
2) Check overall details of the sales order and save it.
3) Click Display document flow.
4) Sales order, invoice and accounting document are created.
1-1. How to generate accounting document.
Because of some errors in billing document accounting document can't be generated.
After correcting the error, you should to generate manually by VF02
2. Create Credit memo.
1) Input credit memo no. and execute it.
2) Check overall details of the credit memo and save it.
2-1. Display & print document by VF03.
