Spork не может загрузить такой файл?

У меня проблема со spork gem. Каждый раз, когда я запускаю команду spork, я получаю эту длинную ошибку:

evan@TheBeast-Computer:~/rails_projects/sample_app$ spork
Using RSpec
Preloading Rails environment
Loading Spork.prefork block...
cannot load such file -- /home/evan/rails_projects/sample_app/spec_helper (LoadError)
/home/evan/rails_projects/sample_app/spec/spec_helper.rb:57:in `require_relative'
/home/evan/rails_projects/sample_app/spec/spec_helper.rb:57:in `block in <top (required)>'
/home/evan/.rvm/gems/ruby-1.9.3-p194/gems/spork-0.9.2/lib/spork.rb:24:in `prefork'
/home/evan/rails_projects/sample_app/spec/spec_helper.rb:6:in `<top (required)>'
/home/evan/.rvm/gems/ruby-1.9.3-p194/gems/activesupport-3.2.5/lib/active_support/dependencies.rb:245:in `load'
/home/evan/.rvm/gems/ruby-1.9.3-p194/gems/activesupport-3.2.5/lib/active_support/dependencies.rb:245:in `block in load'
/home/evan/.rvm/gems/ruby-1.9.3-p194/gems/activesupport-3.2.5/lib/active_support/dependencies.rb:236:in `load_dependency'
/home/evan/.rvm/gems/ruby-1.9.3-p194/gems/activesupport-3.2.5/lib/active_support/dependencies.rb:245:in `load'
/home/evan/.rvm/gems/ruby-1.9.3-p194/gems/spork-0.9.2/lib/spork/test_framework.rb:138:in `block (2 levels) in preload'
/home/evan/.rvm/gems/ruby-1.9.3-p194/gems/spork-0.9.2/lib/spork/app_framework/rails.rb:8:in `preload'
/home/evan/.rvm/gems/ruby-1.9.3-p194/gems/spork-0.9.2/lib/spork/test_framework.rb:134:in `block in preload'
/home/evan/.rvm/gems/ruby-1.9.3-p194/gems/spork-0.9.2/lib/spork.rb:62:in `exec_prefork'
/home/evan/.rvm/gems/ruby-1.9.3-p194/gems/spork-0.9.2/lib/spork/test_framework.rb:120:in `preload'
/home/evan/.rvm/gems/ruby-1.9.3-p194/gems/spork-0.9.2/lib/spork/run_strategy/forking.rb:25:in `preload'
/home/evan/.rvm/gems/ruby-1.9.3-p194/gems/spork-0.9.2/lib/spork/runner.rb:74:in `run'
/home/evan/.rvm/gems/ruby-1.9.3-p194/gems/spork-0.9.2/lib/spork/runner.rb:10:in `run'
/home/evan/.rvm/gems/ruby-1.9.3-p194/gems/spork-0.9.2/bin/spork:10:in `<top (required)>'
/home/evan/.rvm/gems/ruby-1.9.3-p194/bin/spork:23:in `load'
/home/evan/.rvm/gems/ruby-1.9.3-p194/bin/spork:23:in `<main>'

Вот мой Gemfile:

source 'https://rubygems.org'

gem 'rails', '3.2.5'

gem 'sqlite3'

group :assets do
  gem 'sass-rails',   '~> 3.2.3'
  gem 'coffee-rails', '~> 3.2.1'

  gem 'uglifier', '>= 1.0.3'
end

gem 'jquery-rails'

group :development, :test do
  gem 'rspec-rails',    ">= 2.0.1"
end

group :test do
  gem 'rspec-rails', '>= 2.0.1'
  gem 'spork', '>= 0.8.4'
end

Я не знаю, что делать или как описать мою ситуацию. Но результат, который я вижу в учебнике по Ruby on Rails 3, показывает:

$ spork
Using RSpec
Loading Spork.prefork block...
Spork is ready and listening on 8989!