Wont recognize on my mac

first try other SYSTEMs like xp or ...
if still has the problem

Then,
First reset yours by the Back button;

If not solved;

Reset again by the button, the On the Computer by Fat32 Format, and then Copy the Initial Files that were on your MD when you Bought;

If don't have them, mail me through here :
hamidjoush@yahoo.com

Good luck