Solution : https://service.sap.com/sap/support/notes/525893 (SAP Service marketplace login required)
Key words : 
key figure semantics = 010  category group = kp1  category = em  order type = 00  uom = 'x' 2, menu option smp -> environment -> current settings -> define planning folder, standard data view snp94, interactive planning capacity view, newly defined planning folder, standard planning folder delivered, standard planning area 9asnp02, -> key figures -> detail view, -products' key figure, key figure manually
Related Notes : 
       
| 743266 | Capacity view: Order quantities incorrectly displayed | 
| 561561 | SNP94(2) Manufacture of co-prod.not in 'Production (total)' | 
| 556458 | Capacity view: Display dependent products | 
| 527309 | Error in delivered macros | 
| 508459 | Display of the key figure manufacture of co-products |