Hello Dieter,
I think the problem is the "Invalid Channel Combination!!!" error message. Try to change "phys_chan_config" of timeslot 1 from "SDCCH8" to "TCH/F". From my understanding of verify_chan_comb() "SDCCH8" is not allowed on the same TRX that already has "CCCH+SDCCH4" so I wonder why it is set in the config file (this only applies to the BS11). Sorry, I don't have a ready BS11 configuration at hand right now, so I can't test it.
I'll give this a go and response ASAP!
-Paul