Solution : https://service.sap.com/sap/support/notes/313230 (SAP Service marketplace login required)
Key words : 
additional key words co10, status i0002 'created', wbs element assigned, wbs element, production order, solution implement, consequence, prerequisites, note 167170, implemented
Related Notes : 
       
| 391666 | CO02: No check during assignment of WBS element | 
| 167170 | Prod. order release possible although WBS created |