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.