title: Ruby on Rails: "couldn't find file 'jquery.ui.datepicker'"
body: <p>Okay, this is driving me nuts. I've been following the instructions to install a JQuery datepicker here: <a href="http://railscasts.com/episodes/213-calendars-revised" rel="noreferrer">http://railscasts.com/episodes/213-calendars-revised</a> but I'm getting hung up on this error:</p>
  
  <pre><code>Sprockets::FileNotFound in Verifications#new
  
  couldn't find file 'jquery.ui.datepicker'
    (in /app/assets/stylesheets/application.css:11)
  </code></pre>
  
  <p>Here's application.js:</p>
  
  <pre><code>//= require jquery
  //= require jquery.ui.all
  //= require jquery_ujs
  //= require_tree .
  </code></pre>
  
  <p>Here's application.css:</p>
  
  <pre><code> *= require jquery.ui.datepicker
   *= require_self
   *= require_tree .
  </code></pre>
  
  <p>and in Gemfile:</p>
  
  <pre><code>group :assets do
    gem 'jquery-ui-rails'
  end
  </code></pre>
  
  <p>Anyone see what I'm missing?</p>