Joerg, so you copied the bin files from the "aq/bin/aq_unix_all" source folder into aq/bin? You could try running the quatosTool directly from a command-line to make sure it works. If it does and is in the right place, then perhaps it's some QGC issue. I can check that on my copy and see what happens. That error message (I think from the OS) isn't very informative.
-Max