Can't make HTML5 Audio Tag to work on mobile browsers

I have a web app that uses the HTML5 tag and for some reason while it works fine on Windows and Mac PCs it doesn't work on iOS and Android. Here's a relevant snippet of my code:

Javascript:

            var audioElement = document.querySelector('#audioplayer');
            var source = document.querySelector('#mp3');
            source.src = tokObject._url;
            audioElement.load();
            audioElement.play();

HTML:

            <center><audio id="audioplayer" style="width:480px;">
            <source id="mp3" src="random-placeholder" type="audio/mp3" />
            </audio>
            </center>

Cheers and thanks!