Solution : https://service.sap.com/sap/support/notes/455860 (SAP Service marketplace login required)
Key words : 
abap workbench -> ddic objects -> development -> dictionaryextend, attached source code corrections, source code corrections, material availability dates, connected oltp system, /sapapo/bopbackorder processing, transportation scheduling solution, source code, transportation scheduling, backorder processing
Related Notes : 
       
| 453538 | Backorder processing: Sales order is not updated | 
| 375193 | Backorder processing: Composite SAP note on posting |