the linux client by default will do auto-connect on startup and auto-forward on insertion due to the linux client not having a User configurable USB menu once the session is launched - so I dont think there is a need to specify this on the launch command.
I believe the URI launch should work...
can you advise the full URI you are using to try and launch - there might be a mistake in the formatting? (you can mask the server name/user name if you like).
also ; how are you trying to invoke it? - from a shortcut? or from web browser?
please advise
cheers
peterB