Audio tag GUI not visible

I have included the audio tag on a page as

<audio src='a.mp3' preload='auto'>
</audio>

but its not working, i can't see anything on the page.

But when i include audiojs as

  <script src="/static/js/audiojs/audio.min.js"></script>
  <script>
    audiojs.events.ready(function() {
      var as = audiojs.createAll();
    });

  </script>

I am left wondering why is that so ?