Uncaught TypeError: undefined is not a function in audiojs

Question

I am developing an mp3 player using audiojs. This works fine in IE, Firefox and Chrome but fails in Opera. I gather the ones that work OK support mp3 direct, but Opera falls back on Flash player. The error occurs in the following audio.js code (line 358)

    // IE doesn't allow a method named `play()` to be exposed through `ExternalInterface`, so lets go with `pplay()`.  
    // <http://dev.nuclearrooster.com/2008/07/27/externalinterfaceaddcallback-can-cause-ie-js-errors-with-certain-keyworkds/>
    *audio.element.pplay();*
    audio.settings.play.apply(audio);
  }

If I run the audiojs demo in Opera, which also contains identical code, it works OK!

I have seen the discussions on the subject, and have loaded the js files in the "correct" order, and avoided mimified files, but no help.

    <script src="includes/jquery.js"></script>
    <script src="includes/audio.js"></script>
    <script src="includes/music.js"></script>

jquery.js and audio.js have been freshly downloaded from the originators. Any ideas why this should happen?

The demo program can be seen at "http://www.whitstablemusicsociety.org.uk/playlist/"