[Zope] manage_defined_roles pb.

Hello, I've created a Zclass, with a need for some roles. So i've created a setup method (localized on the root folder) for adding this role. Looking at the ZMI code shows that this should work. <dtml-call "REQUEST.set('role','PopotoGest')"> <dtml-call "REQUEST.set('submit','Add Role')"> <dtml-call "manage_defined_roles(REQUEST['role'],REQUEST['submit'],)"> This raise no error BUT doesn't create the role. Did I missed something ? And what ? Thanks in advance.