Redmine

Dear Everyone,
I am following the guide on, https://wiki.ousli.org/index.php/Redmine_in_Ubuntu_Jaunty_9.04. I am a ruby n00b

I followed everything until
rake db:migrate RAILS_ENV="production"

and the error I am getting is:
@(in /var/www/redmine)
rake aborted!
Could not find RubyGem rack (~> 1.0.1)

(See full trace by running task with --trace)
@

my ruby is 1.8.7 and I am running ubuntu karmic.

• Invoke redmine:load_default_data (first_time)
• Invoke environment (first_time)
• Execute environment
  rake aborted!
  Could not find RubyGem rack (~> 1.0.1)
  /var/www/redmine/config/../vendor/rails/railties/lib/initializer.rb:271:in `require_frameworks'
  /var/www/redmine/config/../vendor/rails/railties/lib/initializer.rb:134:in `process'
  /var/www/redmine/config/../vendor/rails/railties/lib/initializer.rb:113:in `send'
  /var/www/redmine/config/../vendor/rails/railties/lib/initializer.rb:113:in `run'
  /var/www/redmine/config/environment.rb:20
  /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
  /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `require'
  /var/www/redmine/vendor/rails/activesupport/lib/active_support/dependencies.rb:156:in `require'
  /var/www/redmine/vendor/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in'
  /var/www/redmine/vendor/rails/activesupport/lib/active_support/dependencies.rb:156:in `require'
  /var/www/redmine/vendor/rails/railties/lib/tasks/misc.rake:4
  /usr/lib/ruby/1.8/rake.rb:617:in `call'
  /usr/lib/ruby/1.8/rake.rb:617:in `execute'
  /usr/lib/ruby/1.8/rake.rb:612:in `each'
  /usr/lib/ruby/1.8/rake.rb:612:in `execute'
  /usr/lib/ruby/1.8/rake.rb:578:in `invoke_with_call_chain'
  /usr/lib/ruby/1.8/monitor.rb:242:in `synchronize'
  /usr/lib/ruby/1.8/rake.rb:571:in `invoke_with_call_chain'
  /usr/lib/ruby/1.8/rake.rb:588:in `invoke_prerequisites'
  /usr/lib/ruby/1.8/rake.rb:585:in `each'
  /usr/lib/ruby/1.8/rake.rb:585:in `invoke_prerequisites'
  /usr/lib/ruby/1.8/rake.rb:577:in `invoke_with_call_chain'
  /usr/lib/ruby/1.8/monitor.rb:242:in `synchronize'
  /usr/lib/ruby/1.8/rake.rb:571:in `invoke_with_call_chain'
  /usr/lib/ruby/1.8/rake.rb:564:in `invoke'
  /usr/lib/ruby/1.8/rake.rb:2027:in `invoke_task'
  /usr/lib/ruby/1.8/rake.rb:2005:in `top_level'
  /usr/lib/ruby/1.8/rake.rb:2005:in `each'
  /usr/lib/ruby/1.8/rake.rb:2005:in `top_level'
  /usr/lib/ruby/1.8/rake.rb:2044:in `standard_exception_handling'
  /usr/lib/ruby/1.8/rake.rb:1999:in `top_level'
  /usr/lib/ruby/1.8/rake.rb:1977:in `run'
  /usr/lib/ruby/1.8/rake.rb:2044:in `standard_exception_handling'
  /usr/lib/ruby/1.8/rake.rb:1974:in `run'
  /usr/bin/rake:28
  @