no AX.25 port data configured?

[cybersake]

Hello Linux-hams,

I just bought SuSE 6.1 with kernel 2.2.5.
I'm trying to get my Serial 1200 baud Baycom modem working with SuSE
linux.
I red the ax-25 Howto and followed the instructions there.
When I try #listen I see packets passing by (so far so good).
But when I try: 
#call bcsf0 PA3ESF

I get: 
no AX.25 port data configured.

bcsf0 is the baycom modem device

Any tips what is causing this message?

How do I configure AX.25 port data?

Many Thanks in advance,
73 Sake PE1MNF