The audio file was encoded as mono 20.05khz. For best computability, you should encode as stereo or joint stereo at 44.1khz. There should be a setting in whatever program you use to encode your mp3 file.
It did play for me if I hit the download button. It also could be your web server is not setup for bit serving. This may make streaming impossible or at least REALLY SLOW. You should put your media on a media hosting account. Blubrry offers hosting here:
https://secure.blubrry.com/podcast-publishing-premium-with-hosting/-Mike