uninitialized constant error with restful authentication

I'm trying to set up restful authentication with Rails 2.1.0 on Mac OS X
Leopard, and I had to comment out RAILS_GEM_VERSION in the environment
file to install the plugin from technoweenie. Now I'm trying to follow
along in a tuturial, and I'm stuck on this:

   1. $ ruby script/generate scaffold Role rolename:string
   2.
/Library/Ruby/Gems/1.8/gems/activesupport-2.1.0/lib/active_support/dependencies.rb:492:in
`const_missing': uninitialized constant User::Authentication (NameError)
   3. from
/Users/naijaguy/Sites/rails_apps/testauthapp/app/models/user.rb:4
   4. from
/Library/Ruby/Gems/1.8/gems/activesupport-2.1.0/lib/active_support/dependencies.rb:215:in
`load_without_new_constant_marking'
   5. from
/Library/Ruby/Gems/1.8/gems/activesupport-2.1.0/lib/active_support/dependencies.rb:215:in
`load_file'
   6. from
/Library/Ruby/Gems/1.8/gems/activesupport-2.1.0/lib/active_support/dependencies.rb:354:in
`new_constants_in'
   7. from
/Library/Ruby/Gems/1.8/gems/activesupport-2.1.0/lib/active_support/dependencies.rb:214:in
`load_file'
   8. from
/Library/Ruby/Gems/1.8/gems/activesupport-2.1.0/lib/active_support/dependencies.rb:95:in
`require_or_load'
   9. from
/Library/Ruby/Gems/1.8/gems/activesupport-2.1.0/lib/active_support/dependencies.rb:260:in
`load_missing_constant'
  10. from
/Library/Ruby/Gems/1.8/gems/activesupport-2.1.0/lib/active_support/dependencies.rb:467:in
`const_missing'
  11. ... 28 levels...
  12. from
/Library/Ruby/Gems/1.8/gems/rails-2.1.0/lib/commands/generate.rb:1
  13. from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:27:in
`gem_original_require'
  14. from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:27:in
`require'
  15. from script/generate:3

Was something (e.g. Authentication) not included when I downloaded the
plugin? I added this line to my ApplicationController:

include AuthenticatedSystem