Problem connecting Western Digital Passport to a MacBook

[LSUtigers03]

A few days ago the hard drive was working fine, but now it won't connect at all. I've tried using different usb cords and different usb ports. I plugged it up to my roommates MacBook and it connected. Then I tried it again a few minutes later on his MacBook and now it doesn't connect to that either. Is there anything else I can try to get it to connect?

 

[Remedy156]

On the passport, do the little LED's on the side light up?

 

[LSUtigers03]

There's only one light on the passport it's next to the mini usb plug. It lights up but it flashes from bright to dim.