[Zope] Unless not quite the opposite of if?

[Curtis Maloney]

Greetings,

	I'm sure this should be obvious to me... but I can't seem to get this code 
to work.  It's supposed to send you to another page if a var has not been 
passed...

<dtml-unless parmName>
  <dtml-call "RESPONSE.redirect('some.url.here')">
</dtml-unless>

The problem is, when i test the page, it seems to pass over that that, and go 
right on with the page.  So, I tried to be a little more explicit:

<dtml-unless "REQUEST.has_key('parmName')">
  ...
</dtml-unless>

Again... goes straight through.  What's going on here?  When I use:

<dtml-if parmName>

(as I have done in MANY cases), it always evaluates true if 'parmName' exists 
in the current context.

Bring out that ol' clue stick, and swing it my directions a few times, 
because I need help.

-- 
Have a better one,
	Curtis.

<dtml-var standard_work_disclaimer>