[Zope] problems implementing my own tag

hello, i have some problems implementing my own tag: zope accepts it but when i write the following in a dtml file: <!--#tag--> hello <!--#var title_or_id--> <!--#/tag--> instead of "hello index_html" i get an array with three elements: "hello ", ('title_or_id'), '\12'. is there a function which parses something like this or is there something i forgot. regards, pawel