Solution : https://service.sap.com/sap/support/notes/388894 (SAP Service marketplace login required)
Key words : 
manufacturing additional key words /sapapo/bop, prerequisites program error solution correctionfirst create, functional group /sapapo/rrp_atp, development class /sapapo/rrp_gui, function module /sapapo/rrp_bob_plan_start, function module /sapapo/rrp_bob_multilvl_post, function module /sapapo/dm_atp_update_bop, function module /sapapo/rrp_bop_new_luw, function module /sapapo/sdorder_items_process, program /sapapo/rrp_bop_plan
Related Notes : 
       
| 497590 | Backorder processing: update status not set | 
| 409792 | Backorder processing: Update status not set | 
| 399014 | 'Syntax for object names not possible' with FG INCLUDES | 
| 385599 | Backorder processing: Planning orders not deleted | 
| 384187 | Backorder processing: Planned orders not saved | 
| 375193 | Backorder processing: Composite SAP note on posting |