Maurice,
Are you trying to connect to a database on another server using TCP/IP ports? If so does the computer that you are getting the error on have TCP/IP installed for the adapter you are using? Does the port number that you are using have a service name in the SERVICES file on your PC (and is it the same name and number as on the Progress server?).
Thats all I can think of at the moment, let me know if this is any help.
JM.