From the help file:
The -tM switch limits the command to being performed only on servers with a certain connection status, where M is an or'd value of 1 = server connected, 2 = not connected, 4 = connecting, 8 = not connecting.The command is only performed if M matches the connect status of the connection id.
Although Khaled tried to hide it well, you can notice the "or'd" in there. It means that you have to apply the OR operator between the numbers you want. If you don't know what OR is, you can just add these numbers together. For example, to make /scon act on "connected" or "connecting" sessions, use 5. (1+4):
/scon -at5 /command