package isdnlog 1:3.12.20071127-0ubuntu8 failed to install/upgrade: subprocess installed post-installation script returned error exit status 255

Binary package hint: isdnutils

(maybe superfluous - or insufficient - but here goes...)
plugged grey oval ISDN TA218 adapter "ISUS93" into usb port of ubuntu 11.04 system. dmesg indicated modules for hisax duly loaded. tried to run isdnlog - not present - proceeded to install it with "sudo apt-get install isdnlog" .. it failed to install fully.
...
* Starting isdnlog... isdnlog/dev/isdnctrl: No such device
invoke-rc.d: initscript isdnutils, action "start" failed.
dpkg: error processing isdnlog (--configure):
 subprocess installed post-installation script returned error exit status 255
Processing triggers for menu ...
Errors were encountered while processing:
 isdnlog
E: Sub-process /usr/bin/dpkg returned an error code (1)

ProblemType: Package
DistroRelease: Ubuntu 11.04
Package: isdnlog 1:3.12.20071127-0ubuntu8
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic-pae 2.6.38.2
Uname: Linux 2.6.38-8-generic-pae i686
NonfreeKernelModules: nvidia
Architecture: i386
Date: Sun May 15 14:42:01 2011
ErrorMessage: subprocess installed post-installation script returned error exit status 255
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release i386 (20101007)
SourcePackage: isdnutils
Title: package isdnlog 1:3.12.20071127-0ubuntu8 failed to install/upgrade: subprocess installed post-installation script returned error exit status 255
UpgradeStatus: Upgraded to natty on 2011-05-02 (12 days ago)