How can I create new ROLE on Window Azure Active Directory?

I try to add new Role 
   var role = Role.CreateRole("6e5f96e0-c084-452a-99a3-a1ee8d59ec88");
   DirectoryService.AddToroles(role);
   DirectoryService.SaveChanges();
But it throw exception:
"Data contract version does not allow 'Create' operations against instances of resource 'Role'"
How can I create new custom ROLE to window Azure Active Directory.
I can not find any Cmdlet(PowerShell) : http://technet.microsoft.com/en-US/library/jj151815.aspx support create new ROLE also