Solution : https://service.sap.com/sap/support/notes/74859 (SAP Service marketplace login required)
Key words : 
additional key words ck11, prerequisites solution install, standard cost estimate, cost estimate, alternative items, input probabilities, repair provided, full quantities, quantities, notes 73960
Related Notes : 
       
| 115011 | CK11: Usage probability for alternatives | 
| 100996 | Alternative item with usage probability in costing | 
| 74062 | BOM explosion; Usage probability | 
| 73960 | BOM explosion; Usage probability |