title: Active admin install error
body: <p>I have an error, when try to run command:</p>
  
  <p><code>rails g active_admin:install</code></p>
  
  <p>The error is:</p>
  
  <blockquote>
    <p>user@user1:~/projectX$ rails g active_admin:install
              invoke  devise
        /home/user/.rvm/gems/ruby-2.2.0/bundler/gems/activeadmin-6bde1f57ec5f/lib/generators/active_admin/devise/devise_generator.rb:21:in <code>rescue in install_devise': uninitialized constant ActiveAdmin::Generators::DeviseGenerator::DependencyError (NameError)
          from /home/user/.rvm/gems/ruby-2.2.0/bundler/gems/activeadmin-6bde1f57ec5f/lib/generators/active_admin/devise/devise_generator.rb:19:in</code>install_devise'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/command.rb:27:in <code>run'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:126:in</code>invoke_command'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:133:in <code>block in invoke_all'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:133:in</code>each'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:133:in <code>map'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:133:in</code>invoke_all'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/group.rb:232:in <code>dispatch'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:115:in</code>invoke'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/group.rb:277:in <code>block in _invoke_for_class_method'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/shell.rb:68:in</code>with_padding'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/group.rb:266:in <code>_invoke_for_class_method'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/group.rb:133:in</code>_invoke_from_option_users'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/command.rb:27:in <code>run'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:126:in</code>invoke_command'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:133:in <code>block in invoke_all'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:133:in</code>each'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:133:in <code>map'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:133:in</code>invoke_all'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/group.rb:232:in <code>dispatch'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/thor-0.19.1/lib/thor/base.rb:440:in</code>start'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/railties-4.2.0/lib/rails/generators.rb:157:in <code>invoke'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/railties-4.2.0/lib/rails/commands/generate.rb:13:in</code>'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:123:in <code>require_command!'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:130:in</code>generate_or_destroy'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:50:in <code>generate'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:39:in</code>run_command!'
          from /home/user/.rvm/gems/ruby-2.2.0/gems/railties-4.2.0/lib/rails/commands.rb:17:in <code>&lt;top (required)&gt;'
          from /home/user/projectX/bin/rails:8:in</code>'
          from /home/user/.rvm/rubies/ruby-2.2.0/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in <code>require'
          from /home/user/.rvm/rubies/ruby-2.2.0/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in</code>require'
          from -e:1:in `'</p>
  </blockquote>
  
  <p>Active admin and devise gems are installed. The only problem is when I generate active admin. I use Rails-4.1.8 and ruby-2.1.4.</p>
  
  <p>Thanks for help and good day.</p>