Audition 1.5 problems....

I use Audition 1.5 and input through an m-audio jamlab (guitarist). With other Audition versions I've tried (2, 3) I can hear what I'm playing whilr recording or playing back another file. In 1.5, However, I can see the VU's jumping when I hit a string, but no audio through the headphones. I use Guitar Rig3 as my amp plug-in, and again in 1.5 only, It'll open, but my jamlab input is not making it to the plug-in (no GR3 input signal displaying on the GR3 VU's). Help!