[Zope] unsettable variable?

[Joh Johannsen]

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