Pads 13-16 not regestering

So, i just got the mpc one and have only played around with the stock sounds and the demo songs cause im not in my studio. For some reason the top four pads(13-16) are unable to assign sounds to, it doesnt matter if its a plugin or a drum program, when i press the other pads the mpc responds and give out a number say a-5..but when i come to pad 13 to 16 it says nothing, its as if they dont exist, i figuered its a setting some where but i cant find it so i thought id ask here, does anybody know what the problem could be?

Load a sample up and select 16 levels option tune, you should be able to test pads 13-16 quickly with that.

If it doesn't work then it may be defective.