Ruby on rails 未初始化的常量Sass:：Plugin

如果我试图推到Heroku，我会犯这个错误。在生产过程中，一切正常

如果我在开发中运行“rakeassets:precompile”，它工作得很好。当Heroku这么做的时候，它失败了

Heroku日志

 /app/vendor/bundle/ruby/2.0.0/bundler/gems/active_admind9c593b13a6f/lib/active_admin/application.rb:258:in `generate_stylesheets': uninitialized constant Sass::Plugin



source 'https://rubygems.org'
ruby '2.0.0'

# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '4.0.0'

# Use postgresql as the database for Active Record
gem 'pg'

# Use SCSS for stylesheets
gem 'sass-rails', '~> 4.0.0'

# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 1.3.0'

# Use CoffeeScript for .js.coffee assets and views
gem 'coffee-rails', '~> 4.0.0'


# Use jquery as the JavaScript library
gem 'jquery-rails', '~> 2.3.0'

# Turbolinks makes following links in your web application faster. Read more: https://github.com/rails/turbolinks
gem 'turbolinks'

# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '~> 1.0.1'

group :doc do
  # bundle exec rake doc:rails generates the API under doc/api.
  gem 'sdoc', require: false
end

gem 'protected_attributes'
gem 'devise',             github: 'plataformatec/devise',     branch: 'rails4'
gem 'responders'       ,   github: 'plataformatec/responders'
gem 'inherited_resources', github: 'josevalim/inherited_resources'
gem 'ransack',             github: 'ernie/ransack',            branch: 'rails-4'
gem 'activeadmin',         github: 'akashkamboj/active_admin', branch: 'rails4'


gem "cancan"
gem 'omniauth'
gem 'omniauth-facebook'

gem 'carrierwave'

---

有灯光吗？没有。奇怪的是我使用的是Rails 4.0。0@Matt我发现它来自主动管理员。但我不知道怎么解决它

gem 'activeadmin',  github: 'gregbell/active_admin', branch: 'rails4'