What APT repository are you talking about?
I am using the debian unstable rep. (official swedish debian mirror).
Yes. When compiling (e.g. jamin) you have to make sure the compile sees the headers and libraries that belong to the distribution's version of JACK (libjack0.80.0-0 and jackd). You have to install libjack0.80.0-dev and make sure you don't have any traces of a previous local install of jack (maybe in /usr/local) left.
I will try that. Thanks for the tip. Djam