dillanova

When I play recordings in Logic Pro 8, I don't get any sound. It accepts my MIDI keyboard, records fine, and the little visualizer jumps up and down when I play the track, as if there is sound. But, as I've stated, there is no sound. I'm currently using a Mac Mini which I purchased in the summer of '06. If it may be a problem with my sound card, I'll pull up the specs, but before I do that, I'm wondering if there may be some other problem associated with this.