[Zope] unsettable variable?

I've got a case like this: <dtml-in get_action_text> <dtml-if expr="action_text=='WIPE_OUT_THIS_VALUE'"> <dtml-call "REQUEST.set('action_text','atest')"> <dtml-call "REQUEST.set('zction_text','ztest')"> action_text is <dtml-var action_text>, zction_text is <dtml-var zction_text> </dtml-if> Here is what shows up for the values when the above is run: action_text is WIPE_OUT_THIS_VALUE, zction_text is ztest Why can I not set the 'action_text'? It really seems like there must be something really obviously stupid in what I am doing, but I just can't see it. Are there cases where a REQUEST.set will have no effect on a dtml-var? Regards, JJ