[Zope] redirect to user's folder not working

[Erik Myllymaki]

I am using this line in my index_html DTML method in the base root folder to
redirect users to their proper folder so content can be specialized for each
of them:

<dtml-call "RESPONSE.redirect(URL1 + '/' + AUTHENTICATED_USER)">

I get an error:

Error Type: TypeError
Error Value: illegal argument type for built-in operation

It works fine like hard-coded like this:

<dtml-call "RESPONSE.redirect(URL1 + '/' + 'username')">


I can use <dtml-var AUTHENTICATED_USER> on the page and get the appropriate
username though?!

Any help appreciated.

-- 
Erik Myllymaki
erik@pacific-shores.com