Multiculturalism works in Canada. I'm not saying there are no problems but
It's always cons or neo-cons who say it doesn't work. Germany's problem is that the system is actively shutting out the Muslims (mainly Turks) because the privileged class wants to keep it that way; and who does the privileged class mostly consist of? Conservatives. If you want integration to happen then some must rise to become part of the aristocracy, otherwise they will just become second class citizens. But this isn't just about that... even on a basic work force level, there is systemic prejudice.
Enclaves happen because cultures have to stick together for survival reasons, and that partially happens because the system is not welcoming enough.