[Zope] parameters X dtml document

Im having some trouble on using URL parameters in zope. What I'm doing: I put in the browser: http://xxxxxxxxxxx.com/document?param=testpage Then in the 'document' page I have the following code: <dtml-var param> Then, what I get in the browser is the strin "testpage", instead of what I wanted, wich would be the content of the 'testpage' document. How can I make the content of test page appear?? Thanks a lot