[Zope] Automatic inclusion help

[M. Adam Kendall]

So here's the situation..
A client wants to automatically include a dtml method
in all dtml documents inside any given folder.  So, using
standard_html_header, I should be able to create some
code to include 'folderid'_html_header.  Right?
Is there something that I am missing here?  For some
reason the dtml-if check doesn't work at all.  I
need to have this check in place, just in case the
object doesn't exist in some folders.

<dtml-comment> Give us folderid_html_header </dtml-comment>
<dtml-let customhead="PARENTS[0].id + '_html_header'">
  <dtml-comment> Check for object </dtml-comment>
  <dtml-if customhead>
     <dtml-comment> Object exists, render object </dtml-comment>
     <dtml-var expr="_[customhead]">
  <dtml-comment> End check </dtml-comment>
  </dtml-if>
<dtml-comment> End namespace injection </dtml-comment>
</dtml-let>

Any ideas?  Or am I going about it completely wrong?

-- 
M. Adam Kendall         |  
mak@kha0s.org           |  "There's never enough time to do
http://kha0s.org        |  all the nothing you want."
                        |   --Bill Watterson (Calvin and Hobbes)