Solution : https://service.sap.com/sap/support/notes/1235375 (SAP Service marketplace login required)
Key words : 
lower-level wbs elements, higher-level wbs elements, superior wbs elements, customer-defined package, attached correction instructions 1020344, co_area - controlling area, activity inputs directly, utility program zaimpldl_struc_ps, project info database, customizing transaction opsb
Related Notes : 
       
| 1620344 | Exit: CJ42 only as init transac for detailed planning of rev | 
| 1392425 | Exit: CJ40 only as init trans for cost elem plng/unit costng | 
| 584655 | Automatic total up without structure plan values | 
| 535158 | CJ40, CJ42: Total up function | 
| 390620 | Not possible to total up outside of structure plannings | 
| 167405 | Unable to total up zero values |