[plt-scheme] Continue tutorial

I'm working through the webserver tutorial, and the sample in the
section "decorating with style" doesn't work.  Specifically, when I
type in test-static.ss, and set up the style sheet file in the htdocs
directory, I still get the following error:

procedure application: procedure: #<procedure:serve/servlet>; does not
expect an argument with keyword #:extra-files-path; arguments were:
#<procedure:start> #:extra-files-path #<path:htdocs> #:launch-browser?
#t

Has something changed since the tutorial was written?  Is there a simple fix?

Thanks,

Mark