monitoring problem

When I record vocals I have no problem monitoring it while recording but when I add a second track and play the keyboard, it records okay but I can not hear it during the recording process. Any ideas what I’m doing wrong?

What you are trying to do is called “overdubbing” (or “overdub recording”). There’s a tutorial in the manual: http://manual.audacityteam.org/man/tutorial_recording_multi_track_overdubs.html