Solution : https://service.sap.com/sap/support/notes/715948 (SAP Service marketplace login required)
Key words : 
terms query 1rowcount exception aggregation multiprovider reason, key performance indicator 1rowcount, 10 content            import support package 14, 0b            import support package 20, exception aggregation cnt, 50            import support package 02, 1 content support package 14, calculated key figure, 0b support package 20, form = 1rowcount
Related Notes : 
       
| 752222 | Key figure 1Rowcount with except. aggr. CNT in non cum.cube | 
| 738075 | 1ROWCOUNT with CNT exception aggregation | 
| 692636 | SAPBWNews BW SP02 NW'04 Stack 02 RIN | 
| 647752 | SAPBWNews BW 3.0B Support Package 20 | 
| 601051 | SAPBWNews BW 3.1 Content Support Package 14 |