MOTU 828: can i hear existing tracks when recording?

[Hoopy]

This might be a basic question. I have the MOTU 828 and an iBook running the bundled Audio Desk software. I can record a track fine. However, when I want to record another track, I can only hear what I am recording and not the track that was already laid down. For instance: I lay down a bass line, I want to hear the bass line while i am recording the guitar part. When I hit record, I can only hear the guitar part that is coming in. Also if I hit play in the timeline, I can only hear the bass line and not the guitar part, so I cannot rehearse the guitar part. i need to hear what I have recorded while I am recording. Is this possible ? I feel like i probably just have a routing problem. It does not mention this in the AudioDesk manual from what I can see.
Thanks,
Hoopy

[Hoopy]

Never mind, I figured it out. For anyone that was curious, I had tracks out of order, so basically it was playing a blank track as I was recording instead of playing a track with music in it. My fault. Oh well at least it works like I want it to.