Solution : https://service.sap.com/sap/support/notes/627607 (SAP Service marketplace login required)
Key words : 
select radio button 'layout editor', change abap dictionary structure comp_dat, frame 'primary objects' add, enter data element co_flg_sim, simulation order ' fiel descr, 'simulation order'definition part, note implements missing corrections, lower-level sales orders, data element co_flg_sim, frame 'secondary objects'
Related Notes : 
       
| 937637 | Changed text of messages COCM 421 and COCM 422 | 
| 629358 | CO47: Simulation order cannot be selected | 
| 498648 | Error during deletion of phantom assemblies |