Which command are you actually passing it? It looks to me like you're trying to 'scp' a file, and Net::SSH::Perl doesnt recognise the command, or that the machine doesn't (doesn't support scp, or the 'scp' command isnt in the PATH for some reason..)
which when executed on the command line of the Alteon gives a screen dump of the current configuration. The message about SCP command message appears whenever I use the $ssh->cmd function (regardless of what command is written).
An interesting thing about this is that if you try and scp command from a shell to the Alteon, the same message is recieved.