[Zope] Starting a dtml-method in a python script

Hi, I ve got a problem: i want to start a dtml-method from a python script.normally it should work like this: container.dtmlmethod() but !!! i always get a "global name REQUEST is not defined error". in the dtml-method are some REQUEST.set calls and it always crashes when my program gets to one of this... if i start the dtml-method normally there are no problems ... so , how do i avoid this error ? Sebastian