hey guys, not sure if any of you have ever had this problem, but someone might know how to fix it.

I record a track onto audacity and theres no problems, i can play it back fine. I then try to record another track over the top of the first track, so i hit record, wait for my time to come in... but I cant hear the first track. The little bar moves over it but i cant hear anything . I checked to make sure its not muted etc, and thats all fine. I can still play It back but just cant hear it when i try to record another track.

anyone know how to fix this?

thanks in advance