you are running the OLD OS 2.8, the players not include the all media format.
All are working from OS 3.2: http://www.lionstracs.com/store/ms-os-32-p-227.html

# MEDIASTATION SYSTEM OS :
# Totally changed the Audio MP3 Players engine library, included now the Hig quality LIBMAD for the Mpg support.
# Totally changed the Audio WAV Players engine library, included now the LIBSNDFILE for the Wav, FLAC, AIFF.
# NEW MS Players able to play now the following file formats: wav, ogg, flac, aiff, aifc, au, snd, raw, paf, * iff, svx, sf, voc, w64, mat4, mat5, pvf, xi, htk, caf, sd2.