[Zope] #tree - trouble

Hi! How come this code (from within index_html) doesn't show files and folders within my folder? <!--#tree branches="objectValues(['Folder', 'File'])"--> <!--#var id--> <!--#/tree--> (<!--#tree--> <!--#var id--> <!--#/tree-->) doesn't work either) This is using Zope 1.10.2 on linux (2.0.35) All I get is a blank screen - how come??