Solution : https://service.sap.com/sap/support/notes/439745 (SAP Service marketplace login required)
Key words : 
additional key words /sapapo/bopi, interactive backorder processing, source code corrections, /sapapo/rrp 3, delivery schedules, updated correctly, prerequisites error, implement note 438999, apo release 3, solution implement
Related Notes : 
       
| 451511 | BOP: Postprocessing is not posted completely | 
| 446299 | BOP: Problems in the postprocessing | 
| 438999 | |
| 435343 | Backorder processing: Item does not exist | 
| 435292 | BOPI: Changes to subitems are not transferred | 
| 432509 | |
| 431807 | BOPI: Incorrect data transfer, COM error | 
| 375193 | Backorder processing: Composite SAP note on posting |