Hey everyone, I'm trying to get Ivory to work in Pro Tools LE 7.3

I create a stereo track, and set the output to ivory, then create a midi track and point it to it, arm the record light, and then when I hit notes on my midi keyboard the MIDI light flashes in Ivory, but it makes no sound and doesn't send any to the stereo audio track.

Can anyone tell me what to do to make this work?