Problem to set up networking features in standalone Win98SE-computer

I am trying to connect an until now stand-alone WIN 98SE -PC to my well
running network. In the stand-alone-PC the PCI-ethernet-Card is already
installed, the driver running. Whenever I click the networking icon in
the system control it shows an error like "The networking option has
been disabled by the system administrator in the system control panel"
(translated freely from german). I then installed all features available
in the Software/Windows-Setup Menu, but without result.
The stand-alone PC is connected to the internet via ADSL/TDSL (via the
well running first PCI-networking card). Could this be the problem ? Can
it be resolved?
Thanks for your help !