@newell:
I connected an old HP Laserjet and printed with it. So I concluded that the card works.

@Blair:
Ah, ok. The decimalcodes of my card are about 60000, so it seems that it could not work ;-).
And that was exactly my question. We wanted to build up new labmachines for the EEG anyway, but I was unsure if I just made a mistake while testing the stuff with existing machines. So no worries, we didn't exchange a mainboard in an existing machine to get the stuff run ;-)
But I must confess that I, apparently, have calculated wrong decimal-values for the hex-values of the I/O-area of my card (SHAME on me).

Anyway, thanks to both of you for your responses,
best,
Tom