Installing internal ISDN on a KX-TD1232

Hi,

I'm in a little trouble because my boss told me to install a ISDN-Fax at our Pansonic KX-TD 1232 telephonesystem. The problem is that I don't know how.

It is a Panasonic KX-TD 1232 with adapted modul for 4SO-Lines (KX-TD 281) and a ISDN-2SO digital super hybrid system (TD- 290?) plugged at the front in the bottomm slot.

I tried some configuration and wiring kombinations given in the manual, but nothing worked.
Does anybody know how to plug/wire and config the system to get the fax working?

Here the things I tried yet:

Wiring at the 281: from bottom to top red, blue. white, yellow (should be 1b, 1a, 2b, 2a) and wired the fax according to this combination.

At the phone:

Systemprogram -> [450] 30 Y-NN (was given in the manual for our config.)
settings in [109] remained default/factory settings: C;C;E1;E2

After a reboot and a short waiting time none of the internal phones worked.

Is there a specific configuration and wiring so that it's possible to get an internal ISDN-Line that has its own MSN?

Thank you very much

Wex