нет такого файла для загрузки - rdoc/task

Когда я запускаю

rake db:create

я получаю эту ошибку

rake aborted!
no such file to load -- rdoc/task

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

Вот --trace

/usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:36:in `gem_original_require'
/usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:36:in `require'
/home/tpeg/rails_apps/Test/Rakefile:8
/usr/lib/ruby/gems/1.8/gems/rake-0.9.2/lib/rake/rake_module.rb:25:in `load'
/usr/lib/ruby/gems/1.8/gems/rake-0.9.2/lib/rake/rake_module.rb:25:in `load_rakefile'
/usr/lib/ruby/gems/1.8/gems/rake-0.9.2/lib/rake/application.rb:495:in `raw_load_rakefile'
/usr/lib/ruby/gems/1.8/gems/rake-0.9.2/lib/rake/application.rb:78:in `load_rakefile'
/usr/lib/ruby/gems/1.8/gems/rake-0.9.2/lib/rake/application.rb:129:in `standard_exception_handling'
/usr/lib/ruby/gems/1.8/gems/rake-0.9.2/lib/rake/application.rb:77:in `load_rakefile'
/usr/lib/ruby/gems/1.8/gems/rake-0.9.2/lib/rake/application.rb:61:in `run'
/usr/lib/ruby/gems/1.8/gems/rake-0.9.2/lib/rake/application.rb:129:in `standard_exception_handling'
/usr/lib/ruby/gems/1.8/gems/rake-0.9.2/lib/rake/application.rb:59:in `run'
/usr/lib/ruby/gems/1.8/gems/rake-0.9.2/bin/rake:32
/usr/bin/rake:19:in `load'
/usr/bin/rake:19

У меня установлены rake 0.9.2 и rdoc 3.11. Я выполняю эти команды в каталоге моего приложения.