Why do my electronic drum sounds, come out of the speakers like regular piano sounds?

When I change my Casio CT-670 midi keyboard to sound like drums and I record into Cubase 3 to make a drum track, when I play it back, it sounds like regular piano sounds. I've only been doing this for a week and its baffling me. Perhaps I need to upgrade my SoundMax to maybe a Creative Soundblaster ? Maybe something inthe settings?