title: Intro.js not working for specific classes
body: <p>I'm not able to start the intro for elements only with class 'case_event_intro' but when I do <code>introJs(".case_event_intro").start();</code> nothing happens, even though there are elements with that class and with the intro att. defined (data-intro and data-step). The elements have also other classes apart case_event_intro. Could that be the problem? Are there any other conditions to make the intro work for only some elements with a given class?</p>
  
  <p>See this <a href="https://dl.dropboxusercontent.com/u/6421243/Intro.js%20not%20working%20for%20specific%20class.png" rel="nofollow">screen capture</a>.</p>