Solution : https://service.sap.com/sap/support/notes/1619616 (SAP Service marketplace login required)
Key words : 
prerequisites rolep authorization object, select model access step, role search reason, model user request, model user, access request, access request 2010, authorization check, symptom create, terms ac10
Related Notes : 
       
| 1642711 | UAM: Model user shows unauthorized roles | 
| 1607067 | Master Note for SAP Access Control 10.0 - Support Pack 6 |