Electronic piano to macbook with midi

Ok so I've got an alesis io 14 firewire interface connected to my macbook. I've got two midi cables connected from the midi ins and outs of the piano to the midi ins and outs of the io 14 (of course the midi in goes to midi out and midi out goes to midi in). I've changed my midi settings properly on the macbook but I still can't seem to get any notes out of the piano onto a midi track in garageband. What do I do? By the way, my piano is a Technics SX-PR500.