VNCviewer tunneling command failed

VNCviewer tunneling command failed

command:
vncviewer -via 192.168.x.x@administrator localhost:0
ssh: connect to host administrator port 22: No route to host
vncviewer: Tunneling command failed: /usr/bin/ssh -f -L
5599:localhost:5900 192.168.x.x@administrator sleep 20.
How can we fix this?