That indicates a connection could not be made, either there is nothing listening on the port at the IP address you have given (ie its not a slingbox or your using a non standard port) or a firewall is blocking the connection from being made. If your on the same network as your slingbox then a tip is to use the local IP address instead of the finder id. If its external then you will need to open the firewall to allow the connection.
Just hooked up my Slingbox Pro, having problems connecting.
"Target machine actively refused it"
Attached file, any thoughts?