Stupid question? What music formats can I use??

[PaulQ]

I saved a bunch of songs to my dInc and they won't play! It says they are not compatible. If anything, the files are lower quality than the music that came on my dInc.

I am using...

MP3
Constant bit rate 192kbs
44.1 Khz / 16 bit
Different encoders but that shouldn't matter.

help??