You left out the .cap file. Your zip only has the .mp3 and the .persist file.
Anyway, .mp3 can only be played by XAudio2 as music, not as a sound. Check out the wiki: http://sourceforge.net/apps/mediawiki/c ... io2_Object
And here's how it's done:
RedText by deadeye (C) 2009
Put your music into a folder called Music or whatever at the same level as your game. This can be either your .cap file or the .exe that you build. It's just, you know... less messy.
When you want to have your XA2 play the music, this is what your music action should look like:
-> XAudio2: Play music AppPath & "\Music\Gears.mp3"
Just to be clear, this is what you type into the expression when you choose the "Play music from file" action: