Amplitube panning stereo/mono question

When I pan tracks with Amplitube in Sonar hard left or right, I still hear the music through the other speaker.  The track is mono and Amplitube claims it's set to mono on the top left of the screen.  I'm only using one amp in Amplitube and one cabinet.  No effects.  There are little "blocks" in the top left corner of Amplitube numbered I believe from 1-6.  I have mine set to the first one because it says mono.  Any ideas?