Music plays on key release not key press

Hi all. I just got a midi keyboard and am trying to play around with it and the mac so I can learn some stuff. I have a Radio Shack MD-1160 keyboard and when I plug it into my mac and run garageband, the music notes won't play until I release the notes on the keyboard.

this is my first mac and midi keyboard so I don't know if this is normal or not. It is kind of distracting when I play the piano lessons and my music doesn't play like it does on the screen.

Anyone have any tips?

thanks