I'm new to Qso net, just a week or so into it.
I've managed to connect an old WW2 RAF Morse key to my computer and it works fine on CQ100. This really is a great addition to any shack in my opinion, long may it continue.
Did you wire your key into your serial port?
Are you using a USB to serial converter?
What software are you using you produce the keyer tones?
Do you notice any lag between pressing the key and hearing the tone?
I Have a serial port on the computer, Not knowing which contacts to use I simply started the program EhoCW and shorted pairs of contacts on the serial port untill I got a tone. Not having a socket/old mouse etc I used some wire coating/sleeve to hold my two wires in place.
I'm not getting any lag at all so all is well and a delight to use.