Solution : https://service.sap.com/sap/support/notes/1443908 (SAP Service marketplace login required)
Key words : 
attached sample code rebuild_weeks_via_rstotl, missing weekly workload data, weekly workload data, daily workload data, relevant support package, key field srtfd, consecutive week number, workload data, data correctly, key transferred
Related Notes : 
       
| 1491908 | ST03n: ABAP-Dump caused by DYNPRO_FIELD_CONVERSION error | 
| 1074808 | SAP Change and Transport Analysis Session: Requirements | 
| 945279 | Workload Collector terminates due to memory problems | 
| 144864 | SAP Remote Services: Technical preparation - ST03 |