Just got my Garritan Jazz and Big Band package. Installed it on my Windows XP system. Every thing installed and activated OK. And, I can insert a VST soft synth track (2 tracks -- one audio, one MIDI) and load up a channel with any instrument and play it in real time on my MIDI keyboard. I can even record from sonar -- the sample plays back while I'm recording. However, Once I try to play it back, no sound. In fact, I don't even have to record -- once I do a "play" in Sonar, the samples won't play back -- not from a track, not real time from the MIDI keyboard, not from the keyboard inside if the Kontact plugin.
By the way, Kontact does seem to recognize that I'm pressing keys on my MIDI keyboard (keyboard lights up and the little MIDI icon flickers). Still no sound, tho.
If it's relevant, I'm using a MOTU Traveler (firewire) for sound. Also, using EZ Drummer, Stylus RMX, TruePianos, ....no problems with any of those. And, my JABB experiment fails even when it's the only thing in my test project.
This might have been the same problem I had a while ago with JABB. I believe if you go to the Projects window. There is a setting (sorry I'm not at my DAW at the moment) that you have to un-check. It says something about zeroing out controller values. Save the project then close the project and open it again. If it still doesn't play sound, then exit Sonar completely and start it again (so that it resets the volumes) for you.