Mainstage 3 with Xpand!2 not working

I installed Air Music Technologies Xpand!2 and it said that it was successfully installed on my computer. However, I cannot see it as an instrument choice in MainStage 3 channel strip. It should be under instrument/AU Instruments/Air Music Technologies/Xpand!2 but it is not there. I have the Native Instruments Kontact sounds installed and they show up fine... But I can't see the Xpand!2 virtual instrument. Any help?