Playing WAV files from USB?

I have an Alpine stereo which i'm unable to get to play WAV files from the USB stick (plays mp3's fine), any ideas? Does the drive have to be formatted a certain way or anything?

EDIT/ seems it wont support WAV, will have to try another format.
 
Convert your wavs to mp3's? Be a smaller file size as well.

I dont like compressed audio, lossless is the only way for me.

Just tried it again with WMA and that wont play either? It clearly states that it should play WMA?

Playback: MP3/AAC/WMA Playback
 
You won't hear the difference between wav/flac and mp3 320 in the car.

Highly unlikely anyway.