If you run debug session through SSH connection and it fails to start, please proceed with the following steps and they will help you identify the problem:
Make sure you set up debugger and IDE to work though SSH (see HOWTO Run Debug Session through SSH)
make sure ssh tunnel, phped and dbglistener are running on the client computer.
make sure sshd (server host) has opened listening socket. Command below should show 7869 port in listening state:
netstat -na|grep 7869
run telnet on the server and make sure it successfully connects back to the dbglistner:
telnet localhost 7869
Immediately after you run telnet you'd see black dot inside the white circle in DbgListener icon and something like "01.01.2004 11:11:14 <serverIP> client connected" in the DbgListener log window.