Problem with HTC MUSIC APP + SONOS

[slm95]

I use the HTC MUSIC APP to steam MP3's to my SONOS ZP90. It works flawlessly with the pre loaded MP3's and the one I bought from the Amazon MP3 store. However, when I put my own MP3s onto the SD card, I can only get them to play locally on the phone, it will not stream it to my SONOS ZP90, it just changes songs till to gets to one of the pre loaded / amazon MP3s.

Anyone know why its doing this and how to fix it?