Solution : https://service.sap.com/sap/support/notes/641910 (SAP Service marketplace login required)
Key words : 
terms short dump reason, dump getwa_not_assigned occurs, stop entry occurs, status = stop, sales orders, crm server, program saplcrm_download_btmbdoc_map, inbound queue, mobile client, program error
Related Notes : 
       
| 663180 | Support Release 01 for CRM 3.1 | 
| 653691 | SAPKU31006: Support Package 06 for CRM 3.1 | 
| 651069 | SAPKU40002: Support Package 02 for CRM 4.0 | 
| 634820 | Downloading into CRM: GETWA_NOT_ASSIGNED dump | 
| 621783 | Upload to R/3: Error in CRM: AM006 "Reference missing..." |