Я успешно установил ActiveAdmin:

Мой код gemfile:

источник 'https://rubygems.org»

 gem 'rails', '3.2.10'

 # Bundle edge Rails instead:
 # gem 'rails', :git => 'git://github.com/rails/rails.git'

 gem 'sqlite3'


 # Gems used only for assets and not required
 # in production environments by default.
 group :assets do
   gem 'sass-rails',   '~> 3.2.3'
   gem 'coffee-rails', '~> 3.2.1'

   # See https://github.com/sstephenson/execjs#readme for more supported runtimes
   # gem 'therubyracer', :platforms => :ruby

   gem 'uglifier', '>= 1.0.3'
 end

 gem 'jquery-rails'

 gem 'twitter-bootstrap-rails'

 gem 'activeadmin'

  # gem "meta_search",    '>= 1.1.0.pre'
 gem "spud_photos"
 gem 'devise'

 gem 'cancan'
 gem 'rolify'

и я сделал это:

 bundle
 rails g active_admin:install
 rake db:migrate
 rails g active_admin:resource product

Я связал некоторые модели с ActiveAdmin.

Ошибка после нажатия в панели управления на ссылку продукта:

 undefined method `per' for #