[Zope] expression evaluation in dtml

[Andy]

hi there,

I <dtml-in...> over a ZSQL-method and get a variable named auth_user from
the database I am accessing.

When I do a
  <dtml-var auth_user>,
it renders 'andyman', as I expected.

Now, when I do a
   <dtml-var "REQUEST.AUTHENTICATED_USER">,
it also renders 'andyman'.

But when I then do a
  <dtml-if "REQUEST.AUTHENTICATED_USER == auth_user "> Hello </dtml-if>,
nothing happens, and that is not what I am expecting.

Can anybody please explain and help me out?

andyman