Resource Manager : Granting switch to a consumer group via a role does not work

Hi,
Config: Oracle 11.2.0.3 EE on Linux and as well on 11.2.0.2 EE on AIX 7.1

Using Resource Manager, I'm having trouble to grant switch to a specific consumer group via a role. Here is what I did:

from the documentation:

If you grant permission to switch to a particular consumer group to a role, then any users who have been granted that role and have enabled that role can immediately switch their current consumer group to the new consumer group.

-- TEST CASE --
SET SERVEROUTPUT ON

BEGIN
-- 1 - Create the pending area
  SYS.DBMS_RESOURCE_MANAGER.clear_pending_area();
  SYS.DBMS_RESOURCE_MANAGER.create_pending_area();