Perhaps you have to reformat your SD card to be compatible with your mp3 player? i.e. Fat or Fat32.
I just purchased a SD 256mb memory card (lexar). I copied music to the card on my computer F:drive. When I put the card in my MP3 player is gives me a error message, "NOTSDAUDIO". What does that mean and how do I get the memory card to work in my MP3 player. The music will play on my computer thru my F:drive.
Thanks for your help.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic