Can't hear 11R along with PT playback?

I'm new to PT and Eleven Rack. Just installed PT 12.2 and 11R rig sound goes mute when I play back a recording and at the same time I play my guitar through 11R. If I actually record a second track as I play first track I can hear the 11R. I've tried arming the input tracking and that doesn't help. This seems like a glitch. Am I missing something? Basically I want to play my guitar against a backing track without recording the guitar, but i can't hear the 11R when I hit play. Please help!

Win 7, 64 bit
Intel i7
4 GB ram