title: "inst is undefined" error in jQuery UI Datepicker
body: <p>I basically have a jQuery Datepicker. The Datepicker shows up but it doesn't seem functional as it does nothing when a day is selected. It doesn't work and previous and next are selected as well.</p>
  
  <p>I get the "<strong><em>inst is undefined</em></strong>" error</p>
  
  <p>-- the script</p>
  
  <pre><code>jQuery(function() {
      jQuery("#datepicker1").datepicker();
  });
  </code></pre>
  
  <p>-- the element</p>
  
  <pre><code>&lt;input type="text" id="datepicker1" name="datepicker1"/&gt;
  </code></pre>