[Zope] ZPT Problem

[beno]

Hi;
I have a python script I call from a page template. Here's the call:

<p tal:replace="structure python:here.contentMacro(template.id)" />

Here's the script:

template_id = template_id[:-4]
if (template_id[:-5] != 'frame')
  template_id = template_id + '_frame'
content = "<p tal:replace='here/" + template_id + "_content/macros/content' 
/>\n"
print content
return printed

If this is called from either *index.zpt* or *index_frame.zpt* it renders 
the following code:

<p tal:replace='here/index_frame_content/macros/content' />

Unfortunately, this code isn't called, just rendered. I would like said 
macro to actually be called (of course). What have I missed?
TIA,
beno