Can't play sound file

I added an mp3 file to my project, but when I try it to play I get this message:

Cannot connect to server socket err = Bestand of map bestaat niet
Cannot connect to server socket
jack server is not running or cannot be started
** Message: don’t know how to handle audio/mpeg, mpegversion=(int)1, mpegaudioversion=(int)1, layer=(int)3, rate=(int)44100, channels=(int)2, parsed=(boolean)true

I’m using Ubuntu 12.04 64bit and I have gstreamer and xine installed.
I also tried it while running Jack, but that also didn’t work