Solution : https://service.sap.com/sap/support/notes/709730 (SAP Service marketplace login required)
Key words : 
error message cave 005 'sourcing main item &, source code corrections, symptom rba, post-processing, update status, solution implement, 'rejected', document &, transferred', prerequisites
Related Notes : 
       
| 375193 | Backorder processing: Composite SAP note on posting |