找不到’jquery-ui’Rails 3.2

我一直在寻找解决这个问题的方方面面.我已经在我的gemfile中将jquery-rails gem降级为2.3.0.但是当我在application.js中包含jquery-ui时,我仍然会收到Sprokets :: FileNotFound错误.

Couldn't find file 'jquery-ui'
  (in /home/richard/projects/pickaxe/mini-projects/depot-app/app/assets/javascripts/application.js:14)

这是我的application.js文件：

// This is a manifest file that'll be compiled into application.js,which will include all the files
// listed below.
//
// Any JavaScript/Coffee file within this directory,lib/assets/javascripts,vendor/assets/javascripts,// or vendor/assets/javascripts of plugins,if any,can be referenced here using a relative path.
//
// It's not advisable to add code directly here,but if you do,it'll appear at the bottom of the
// the compiled file.
//
// WARNING: THE FIRST BLANK LINE MARKS THE END OF WHAT'S TO BE PROCESSED,ANY BLANK LINE SHOULD
// GO AFTER THE REQUIRES BELOW.
//
//= require jquery
//= require jquery-ui
//= require jquery_ujs
//= require_tree .

我很想知道为什么这不起作用……