Your computer could not connect to another console session on the remote computer because you already have a console session in progress.

You can use port tester to verify if computer you are connecting has Remote desctop service available.
1.Download porttester unzip and run (no installation required).
2.Specify computer name and port 3389 (RDP port)
If it will return "Port unavailable" that means there is no physical connection to remote
desktop service on target computer.