Solution : https://service.sap.com/sap/support/notes/356152 (SAP Service marketplace login required)
Key words : 
additional key words bop, attached source code corrections, apo backorder processing, backorder processing, errors occur, program error, solution implement, prerequisites
Related Notes : 
       
| 375193 | Backorder processing: Composite SAP note on posting | 
| 356755 | Incorr.transfer of results of APO backorder proc. | 
| 321913 | Transfer of the backorder processing results |