enabling modules in the Admin or User menu

Hi everyone,

in Admin -> Modules -> Modify properties of Articles, we are able to 
enable the Admin or User menu for Articles.

This works well from the point of view of the admin (I can see my menus 
changing in real time), but nothing changes from the point of view of a 
casual or a user access :
- neither can I remove the Roles menu
- nor can I add the Articles one.

What I am missing?

My installation is a really basic one : Xaraya Core 1.1.3 + Articles & 
Categories + Xaraya_Classic.

Thanks to ALL of you.