[Zope] setHeader not working?!

[alex]

I've tried to use RESPONSE.setHeader('pragma','no-cache') on 2 zope boxes
2.4.1 python 2.1.1 (a linux and a win32) and none works

I test it doing a lynx -head -dump http://myzopebox/myscript
also tried:
telnet myzopebox 80
HEAD /myscript HTTP/1.0

I dont see 'pragma' on the headers, any ideas what's wrong?

I've tried it on python script:
context.REQUEST.RESPONSE.setHeader('pragma','no-cache')
return ''

and also dtml
<dtml-call "RESPONSE.setHeader('pragma','no-cache')">

nothing works.

any hints?

thanks
Alex