Solution : https://service.sap.com/sap/support/notes/385506 (SAP Service marketplace login required)
Key words : 
additional key words bop, data elementlfuhr                   lfuhrin addition, data elementlfuhr                   bapiupdate, delivery time-spot, apo backorder processing, prerequisites solution note 385524, delivery time field, cif_sl_id structure, transaction se11, cif_sl_ix structure
Related Notes : 
       
| 385524 | Backorder processing: delivery time-spot is missing | 
| 375193 | Backorder processing: Composite SAP note on posting |