you need to make the RELEASE version of the juce lib. please look at grace/doc/install.html, section "Building JUCE on Linux", where point 3 says: > 3. Make the Release version of libjuce.a: > > $ cd juce/build/linux > $ make CONFIG=Release > > If you are successful the JUCE library will be saved in juce/bin/ > libjuce.a.