Redmine

I am using this how to guide: http://www.redmine.org/projects/redmine/wiki/HowToInstallRedmineOnUbuntuServer

I'm positive I've followed the instructions properly so far but have run into a road block and haven't been able to find a suitable workaround.

when I get to the step:

Create the database structure, by running the following command under the application root directory:

$ cd /usr/share/redmine

$ sudo rake db:migrate RAILS_ENV="production"

Here's what happens when I input the command:
dmaclure@redmineubuntu:/usr/share/redmine$ sudo rake db:migrate RAILS_ENV="production"

(in /usr/share/redmine)
Please install RDoc 2.4.2+ to generate documentation.
rake aborted!
undefined method `requirement' for #<Rails::GemDependency:0xb76747a8>

when I run the same command with --trace I get:

dmaclure@redmineubuntu:/usr/share/redmine$ sudo rake db:migrate RAILS_ENV="production" --trace

(in /usr/share/redmine)
Please install RDoc 2.4.2+ to generate documentation.
Invoke db:migrate (first_time)
Invoke environment (first_time)
Execute environment
rake aborted!
undefined method `requirement' for #<Rails::GemDependency:0xb74ef658>
/var/lib/gems/1.8/gems/rails-2.3.14/lib/rails/gem_dependency.rb:81:in `add_load_paths'
/var/lib/gems/1.8/gems/rails-2.3.14/lib/initializer.rb:301:in `add_gem_load_paths'
/var/lib/gems/1.8/gems/rails-2.3.14/lib/initializer.rb:301:in `each'
/var/lib/gems/1.8/gems/rails-2.3.14/lib/initializer.rb:301:in `add_gem_load_paths'
/var/lib/gems/1.8/gems/rails-2.3.14/lib/initializer.rb:132:in `process'
/var/lib/gems/1.8/gems/rails-2.3.14/lib/initializer.rb:113:in `send'
/var/lib/gems/1.8/gems/rails-2.3.14/lib/initializer.rb:113:in `run'
/usr/share/redmine/config/environment.rb:24
/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/lib/gems/1.8/gems/activesupport-2.3.14/lib/active_support/dependencies.rb:182:in `require'
/var/lib/gems/1.8/gems/activesupport-2.3.14/lib/active_support/dependencies.rb:547:in `new_constants_in'
/var/lib/gems/1.8/gems/activesupport-2.3.14/lib/active_support/dependencies.rb:182:in `require'
/var/lib/gems/1.8/gems/rails-2.3.14/lib/tasks/misc.rake:4
/usr/lib/ruby/1.8/rake.rb:636:in `call'
/usr/lib/ruby/1.8/rake.rb:636:in `execute'
/usr/lib/ruby/1.8/rake.rb:631:in `each'
/usr/lib/ruby/1.8/rake.rb:631:in `execute'
/usr/lib/ruby/1.8/rake.rb:597:in `invoke_with_call_chain'
/usr/lib/ruby/1.8/monitor.rb:242:in `synchronize'
/usr/lib/ruby/1.8/rake.rb:590:in `invoke_with_call_chain'
/usr/lib/ruby/1.8/rake.rb:607:in `invoke_prerequisites'
/usr/lib/ruby/1.8/rake.rb:604:in `each'
/usr/lib/ruby/1.8/rake.rb:604:in `invoke_prerequisites'
/usr/lib/ruby/1.8/rake.rb:596:in `invoke_with_call_chain'
/usr/lib/ruby/1.8/monitor.rb:242:in `synchronize'
/usr/lib/ruby/1.8/rake.rb:590:in `invoke_with_call_chain'
/usr/lib/ruby/1.8/rake.rb:583:in `invoke'
/usr/lib/ruby/1.8/rake.rb:2051:in `invoke_task'
/usr/lib/ruby/1.8/rake.rb:2029:in `top_level'
/usr/lib/ruby/1.8/rake.rb:2029:in `each'
/usr/lib/ruby/1.8/rake.rb:2029:in `top_level'
/usr/lib/ruby/1.8/rake.rb:2068:in `standard_exception_handling'
/usr/lib/ruby/1.8/rake.rb:2023:in `top_level'
/usr/lib/ruby/1.8/rake.rb:2001:in `run'
/usr/lib/ruby/1.8/rake.rb:2068:in `standard_exception_handling'
/usr/lib/ruby/1.8/rake.rb:1998:in `run'
/usr/bin/rake:28

I've researched a bit and can't seem to isolate what my issue is. Have any of you run into this error before? It's got me stumped.

any tips or help is appreciated.