Suse 9.0 Fritz!DSL and isdnlog

Hi. I have a Fritz!DSL-card. The one with ISDN on Board. Everything works fine besides the isdnlog. I can see, that it is running (ps -A) but no /var/log/isdn.log -File is created. There are no log-entries in messages. with my Fritz!USB isdnlog works fine. I can reproduce that behavior on 3 different PCs with the Fritz!DSL card inside. Does anyone know something, or has a suggestion how to debug this? Sincerly, Axel Spallek.