TCP/IP Connection error

I have created a TCP/IP connection in R/3 using transaction SM59 with destination type 'T'. I used the registration option which has 'Program id' as required field. I specified 'XYZ' in it. When I test the connection it gives me an error saying 'Connection Error - XYZ is not registered'. Can you tell me what is missing?

It sounds like the external server simply has not registered itself. Also remember that the Program ID is case-sensitive.