IP alias and SuSE firewall

Hi List, I need to configure our firwall machine for two different static IP addresses on the same ISDN dial-up interface. The configuration is: SuSE 7.1 SuSE Firewall 4.7 Kernel 2.2.19 I did already configure the alias address for the interface and I can ping or connect to services from the local machine. But any packet coming from the internet via the dial-up line to the secondary IP address is rejected by the firewall (pakets to the primary address pass normally). I tried to configure FW_DEV_WORLD = "ippp0 ippp0:0" but that did not help either. How can I tell the firewall script to accept pakets for the secondary address? Any help is greatly appreciated! Jürgen