Solution : https://service.sap.com/sap/support/notes/395906 (SAP Service marketplace login required)
Key words : 
attached source code corrections, additional key words transaction, function module /sapapo/bop_sched_parameter, call transaction se37, enter /sapapo/bop_sched_parameter, 'import' tab page, material staging date, /sapapo/bop_updatebackorder processing, batch backorder processing, backorder processing
Related Notes : 
       
| 420605 | Composite SAP Note for BOP performance in APO 3.0A | 
| 375193 | Backorder processing: Composite SAP note on posting |