Why won't this gemfile update or install with bundler?

Question

This is my gemfile - I'm working on Michael Hartl's RoR tutorials. I keep getting "Gemfile syntax error:" when I try to bundle install or bundle update. Insight?

    source 'https://rubygems.org'
    ruby '2.0.0'
    #ruby-gemset=railstutorial_rails_4_0

    gem 'rails', '4.0.4'

    group :development, :test do
      gem 'sqlite3', '1.3.8'
      gem 'rspec-rails', '2.13.1'
      gem 'guard-rspec', '2.5.0'
      gem 'spork-rails', '4.0.0'
      gem 'guard-spork', '1.5.0'
      gem 'childprocess', '0.3.6'
    end

    group :test do
      gem 'selenium-webdriver', '2.35.1'
      gem 'capybara', '2.1.0'
      gem 'growl', '2.1.0'
    end

    gem 'sass-rails', '4.0.1'
    gem 'uglifier', '2.1.1'
    gem 'coffee-rails', '4.0.1'
    gem 'jquery-rails', '3.0.4'
    gem 'turbolinks', '1.1.1'
    gem 'jbuilder', '1.0.2'

    group :doc do
      gem 'sdoc', '0.3.20', require: false
    end

    group :production   
      gem 'pg', '0.15.1'
      gem 'rails_12factor', '0.0.2'
    end

Answer 1

Try adding do to the line group :production:

group :production do
  gem 'pg', '0.15.1'
  gem 'rails_12factor', '0.0.2'
end