SanDisk Clip Sport Supported file types

SanDisk MP3 players SanDisk® Clip Sport
11

Several Ogg Vorbis files that work fine on my workstation and on my old Sansa Fuze do not play on my new SanDisk Clip support.

I can see nothing the files have in common.

Any idea what the problem might be?

Thanks,

BruceByfield