New vocal track in old project is silent

I opened a project in Sonar X3 64bit which was previously recorded in Sonar X1 32bit and attempted to add a new vocal track.  But I can't get anything recorded on that new audio track.  I know my mic and my Fast Track Pro interface are working because I had no problem recording a vocal track in a brand new project.  And any sound made in front of the mic shows up on the volume level meters.  But trying to record a new track on the old project gives me only silence on the audio track and no wave image.
 
I tried opening the project in the 32 bit version of X3 but the result was no different.  Does anyone have any idea what my problem is?  Shouldn't I be able to work on an older project in a newer version of Sonar?  Thanks.

Thanks, Larry, I think you hit the nail on the head.  I had previously noticed it was on and turned it off, but somehow in going back and forth between 64bit and 32bit, it turned itself back on.  Amazing how one unnoticed thing can totally interrupt your progress.  It's okay now.