Solution : https://service.sap.com/sap/support/notes/539442 (SAP Service marketplace login required)
Key words : 
img path cross-application components -> general application functions -> cross application document numbering -> argentina -> define document classes, img path cross-application components -> general application functions -> cross application document numbering -> maintain document classes, img path cross-application components -> general application functions -> cross application document numbering -> assign document class, img path financial accounting -> financial accounting global settings -> document -> document header -> check assignment, official document numbering generation, argentinian document numbering stored, official document numbering, application, create data element j_1aforcenum, document class
Related Notes : 
       
| 594358 | Document ref. number (XBLNR) initialized for SD credit memos | 
| 578178 | Document ref. number (XBLNR) initialized after SP39/4.6C | 
| 571376 | Official Document Numbering - new customizing tables | 
| 406115 | Transfer of billing docs to FI: Reference number is missing | 
| 389445 | Official doc.numbering: SD billing with net value 0 |