Is working now ;-)
thx guys for your help!!!
The problem was really simple!
It´s called $XP ;-(
There is no chance to get entrance to hardware (com-port etc.) in XP.
Si i take a Win98 machine, started it in Dos-mode and....running. ;-)
All bands free now!
Will now try if ex1726 will run under XP with the dosenabler by www.kithara.de/ge/kdos.htm