Solution : https://service.sap.com/sap/support/notes/113369 (SAP Service marketplace login required)
Key words : 
field/structure   proposal    optional i_no_account_assignment   eban-xoblr             space         xactivate, -stock components procured directly, additional key words co40, material requirements planning, function modules me_read_requisition_ext, import parameter          ref, table eban, import parameter, function modules, planned order
Related Notes : 
       
| 101803 | Double accnt assignment f.PReq without material no | 
| 101170 | BAPI_REQUISITION_CHANGE terminates uncontrolled |