Judging from other posts on your forum, GarageBand still remains a problem for Eventide Blackhole, and thus is not a proper test for validating AU.

I succesfully loaded the VST in MuTools MuLab Free (http://www.mutools.com/mulab-downloads.html), and the AU in JU-X Hosting AU application (http://ju-x.com/hostingau.html).