music on the external drive not recognized

i am able to load music on the external micro drive I bought using software though not using explorer. I get an error message when I use explorer.  It also plays using media monkey just fine.  When I put it in my new Sansa clip it says the disc is empty.  What am I doing wrong?

well I now have gotten the disk to read and take data using explorer but none of the music shows up on the sansa clip so i still am not doing something right.