Homematic with CCU1

I’m totally stuck with my configuration. I have a homematic installation based on CCU1 and run OpenHAB on a windows machine. I can connect to the webinterface of my CCU1 under http://homematic/ and the webapp under http://localhost:8080/
Based on the demo, I configured one HM-CC-TC and HM-CC-VD. It received once a temperature and I saw it in the webapp, but now it only shows empty values.
I started the server with start_debug.bat and added
<logger name="org.openhab.binding.homematic" level="TRACE" />
to logback_debug.xml, but nothing related to homematic appeared in the console.
I seem to be editing the correct .items-file because changes in the captions appear in the webapp.

Does anyone have an idea what I might be doing wrong?