It's seem that Sonar Professional won't render my Konpakt instruments to audio tracks or a stereo file! Don't know if this a bug or if I'm doing anything wrong but I get a audio track and or file that's empty!

The most common cause for this among new users is that they have not properly set the output of the virtual instrument as the input of an audio track, or arm the track to record. It is impossible to guess what your particular problem might be, since you have provided no description whatsoever of how you are trying to do whatever it is you are failing to accomplish.

Hi. As mentioned above, we need more info before we can be of any assistance. How are you routing your MIDI track to your soft synth? Are you using simple instrument tracks, or do you have separate audio and MIDI tracks? How do you render your tracks? Is both MIDI and Vsti selected? The more info, the easier to help.
Best of luck.

Also, if you are bouncing to track, don't forget that you have to select both the midi and the VST track. Selecting just the midi will either give you a warning that there is no audio, or deliver an empty wave file. It depends on what was selected. If both tracks are selected, make sure the selection range is correct and that all of your midi clips are also selected.
 
Regards,
Dan