Solution : https://service.sap.com/sap/support/notes/596323 (SAP Service marketplace login required)
Key words : 
incorrect data exchange, data exchange, crm billing, terms bem_upload_fi_srv, bapi_bill_doc_proxy_create reason, accounting, bem_download_bea_fill, bill_doc_inbound, prerequisites, /3 accounting
Related Notes : 
       
| 608555 | |
| 594533 | Transfer of CRM billing documents terminates | 
| 592150 | |
| 554992 | |
| 536725 | Runtime error: Field symbol has not yet been assigned. | 
| 450560 | |
| 414606 |