NameError in Rails/infoController#properties ( uninitialized constant ActiveRecord::Base::SQLite3 )

I am trying to setup my RubyOnRails environment as mentioned in the
RailSpace book ( RailsSpace: Building a Social Networking Website with
Ruby on Rails ), pg 18. However when I click on the "About your
application's environment" link, I get the following :

NameError in Rails/infoController#properties

uninitialized constant ActiveRecord::Base::SQLite3

sqlite3 is setup correctly, I am able to create my own database and
query it.

With Mongrel I get this stack trace :

Processing InfoController#properties (for 127.0.0.1 at 2008-08-01
14:41:02) [GET]
  Session ID:
BAh7BiIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNo
SGFzaHsABjoKQHVzZWR7AA==--41dd781d7835c4f0356f92927fa3dbfd6ae447a0
  Parameters: {"action"=>"properties", "controller"=>"rails/info"}

Processing InfoController#properties (for 127.0.0.1 at 2008-08-01
14:41:02) [GET]
  Session ID:
BAh7BiIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNo
SGFzaHsABjoKQHVzZWR7AA==--41dd781d7835c4f0356f92927fa3dbfd6ae447a0
  Parameters: {"action"=>"properties", "controller"=>"rails/info"}

NameError (uninitialized constant ActiveRecord::Base::SQLite3):
    /usr/local/lib/ruby/gems/1.8/gems/activesupport-2.1.0/lib/
active_support/dependencies.rb:492:in `const_missing'
    /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.0/lib/
active_record/connection_adapters/sqlite3_adapter.rb:13:in
`sqlite3_connection'
    /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.0/lib/
active_record/connection_adapters/abstract/connection_specification.rb:
292:in `connection='
    /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.0/lib/
active_record/connection_adapters/abstract/connection_specification.rb:
260:in `retrieve_connection'
    /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.0/lib/
active_record/connection_adapters/abstract/connection_specification.rb:
78:in `connection'
    /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.0/lib/
active_record/query_cache.rb:8:in `cache'
    /usr/local/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/
action_controller/caching/sql_cache.rb:12:in `perform_action'
    /usr/local/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/
action_controller/base.rb:529:in `process_without_filters'
    /usr/local/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/
action_controller/filters.rb:569:in
`process_without_session_management_support'
    /usr/local/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/
action_controller/session_management.rb:130:in `process'
    /usr/local/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/
action_controller/base.rb:389:in `process'
    /usr/local/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/
action_controller/dispatcher.rb:149:in `handle_request'
    /usr/local/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/
action_controller/dispatcher.rb:107:in `dispatch'
    /usr/local/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/
action_controller/dispatcher.rb:104:in `dispatch'
    /usr/local/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/
action_controller/dispatcher.rb:120:in `dispatch_cgi'
    /usr/local/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/
action_controller/dispatcher.rb:35:in `dispatch'
    /usr/local/lib/ruby/gems/1.8/gems/mongrel-1.1.5/bin/../lib/mongrel/
rails.rb:76:in `process'
    /usr/local/lib/ruby/gems/1.8/gems/mongrel-1.1.5/bin/../lib/mongrel/
rails.rb:74:in `process'
    /usr/local/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:
159:in `process_client'
    /usr/local/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:
158:in `process_client'
    /usr/local/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:
285:in `run'
    /usr/local/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:
285:in `run'
    /usr/local/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:
268:in `run'
    /usr/local/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/
configurator.rb:282:in `run'
    /usr/local/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/
configurator.rb:281:in `run'
    /usr/local/lib/ruby/gems/1.8/gems/mongrel-1.1.5/bin/mongrel_rails:
128:in `run'
    /usr/local/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/
command.rb:212:in `run'
    /usr/local/lib/ruby/gems/1.8/gems/mongrel-1.1.5/bin/mongrel_rails:
281
    /usr/local/lib/ruby/gems/1.8/gems/activesupport-2.1.0/lib/
active_support/dependencies.rb:502:in `load'
    /usr/local/lib/ruby/gems/1.8/gems/activesupport-2.1.0/lib/
active_support/dependencies.rb:354:in `new_constants_in'
    /usr/local/lib/ruby/gems/1.8/gems/activesupport-2.1.0/lib/
active_support/dependencies.rb:502:in `load'
    /usr/local/lib/ruby/gems/1.8/gems/rails-2.1.0/lib/commands/servers/
mongrel.rb:64
    /usr/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in
`require'
    /usr/local/lib/ruby/gems/1.8/gems/activesupport-2.1.0/lib/
active_support/dependencies.rb:509:in `require'
    /usr/local/lib/ruby/gems/1.8/gems/activesupport-2.1.0/lib/
active_support/dependencies.rb:354:in `new_constants_in'
    /usr/local/lib/ruby/gems/1.8/gems/activesupport-2.1.0/lib/
active_support/dependencies.rb:509:in `require'
    /usr/local/lib/ruby/gems/1.8/gems/rails-2.1.0/lib/commands/
server.rb:39
    /usr/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in
`require'
    script/server:3

Rendering /usr/local/lib/ruby/gems/1.8/gems/actionpack-2.1.0/lib/
action_controller/templates/rescues/layout.erb (internal_server_error)

I am totally new to Ruby on Rails, so have no clue on what to fix.
From the above it appears that I don't have the SQLite3 environment
setup correctly for Rails. Any idea on what I need to setup ?

Thanks.