Mac Mini system sound not playing from Digi 002
 

I have a mac mini, running mac osx 10.5.8, I have pro tools 8.0.1, and a Digi 002. I hear audio fine from the Digi 002 when I use all my applications (Itunes,ProTools, Reason, Logic etc.) But I don't hear the system sounds even though I have the Digi 002 selected from sound in the system preferences. I can't figure it out. Any help will be greatly appreciated.