[plt-scheme] error message installing web-server

I'm running Debian stable (currently etch) on an AMD-64 system, with 
drscheme and mzscheme installed.  Now I decide I want to activate 
mzscheme's web-server to try it out.  Earlier, I asked for it not to 
start on boot.

I reconfigure mz-scheme:

april:~# dpkg-reconfigure mzscheme

Stopping web server: web-server ... No /usr/bin/mzscheme found running; 
none killed.
done.
Cataloging SLIB routines...
reference to undefined identifier: slib:features
april:~# 

and, as far as I can tell, no web server is running.  In particular, 
when I use my browser to access http://localhost:8000, I am told it is 
unable to connect to localhost (port 8000).

Is the slib problem queering things, or is something else wrong?

-- hendrik