[Zope] dtml-tree & skip unauthorized

Hello, I would like to make a site map for my plone site (with Zope 2.7.2 and Plone 2.0.4) with the dtml-tree function... When I tried my code, it's successful with the administrator count but it raise an exception "An error occurred. Error type: Unauthorized Error value: You are not allowed to access 'Documentation' in this context", although I use the "skip unauthorized" in the declaration of the dtml-tree tag. I also try to use skip unauthorized=1 with no more success. Is someone can help me ? Sorry for my English Stéphane