My new 60GB Failed?

HI, i just recently bought a second hand 60GB HDD of someone for my xbox 360, when i plugged it in it worked, but it had all his data on it.

So i just formatted it, and moved my old saved games to it. But now when its plugged in the top, it doesnt even recognise the HDD.

The only way i can play games is trough transfer cable, but even then it only recognises as a 16GB USB device. And i cant download Content to it.

So my 60GB is now only 16GB and i dont see how ive done anything wrong, i done the most obvious thing to do.

So please someone help me!!