RE: Issue installing Add-on 3 to G2
Don,
I recently installed G2 on a new PC ... I installed G2 first, then upgraded to the latest version (had to manually download the control panel to get to server #2), then all 5 add-ons installed fine.
Did you upgrade to the latest patch before installing the add-ons? Not sure this will help, just an idea.
Good luck!
Carl