Solution : https://service.sap.com/sap/support/notes/1147419 (SAP Service marketplace login required)
Key words : 
unselected key fields, source key figures, source datastore object, source key fields, data transfer process, terms incorrect data, transfer data, source data, target fields, incorrect results
Related Notes : 
       
| 1286388 | BI7.0(21): DTP extraction from DataStore without aggregation | 
| 1178077 | Effect of start routine on performance and extraction |