Audition CC 2017 won't play previous tracks when recording new track

[ryanthevegan]

I recorded the guitar part of a song and then unclicked the 'R' on that track.  Clicked the 'R' for the vocal track and hit record.  But nothing plays.  If I just click play, it plays the guitar part.  But, not if I'm recording.  Any ideas?  I'm using Windows 10.

[Bob Howes]

What are using  by way of a sound card or audio interface?  It's the routing through that that's probably where the problem lies.