Solution : https://service.sap.com/sap/support/notes/819480 (SAP Service marketplace login required)
Key words : 
sapbwnews bw sp12 netweaver'04 stack 12, runtime error convt_no_number occurs, 0b            import support package 27, 10 content            import support package 21, <g_nnn> eq <g_c_nnn_mmm>, terms query reason, provide advance information, 50            import support package 12, 0b support package 27, sapbwnews bw 3
Related Notes : 
       
| 763340 | SAPBWNews BW Support Package 12 NetWeaver'04 Stack 12 RIN | 
| 723263 | SAPBWNews BW 3.1 Content Support Package 21 | 
| 723258 | SAPBWNews BW 3.0B Support Package 27 |