Hm, tricky sort of question to answer as it stands. Can you try the "vamp-simple-host" command-line host, or the vamp-plugin-tester, or else try running Sonic Visualiser from a terminal window? (To do the latter, run the program at "Sonic Visualiser.app/Contents/MacOS/Sonic Visualiser" in the SV bundle.)
Any of these should give you some more useful information at the terminal which indicates why it can't load your plugin.
Chris