That was indeed part of the problem. I installed the display on the main pi (the one with the squeezebox-server). Later I installed the RPI-Display Plugin and selected the Display-after that the display showed the linux boot-process, went to a black screen with a cursor – but it did not start any services like webserver, squeezebox-server, etc. so i did not get any chance to activate jivelite etc.
I disconnected the display now and did not try it again. Do you have any idea why it did not boot any further?