I'd expect a "SQL Server does not exists or access denied" errormessage but yours even suggests an error in a procedure. I really wonder how the sp comes into play, I'd suggest you remove the @@Servername and change it into the name of the server instead. @@Servername is not (directly) available from a command-prompt.
That could explain why the errormessage indicates a fault in the sp: you're running it from the sp. I have a case where @@servername is NULL btw, don't know how bad that is, but concatting a null to var/char usually results in a null var/char. The parameter -T might also help authenticating. Other than that, I don't see what's wrong but I don't know much about 6.5.
A lot would depend on what error the 6.5 machine coughed up when you tried to run it... For one thing, the queryout parameter wasn't supported on 6.5, and it was a lot touchier about authentication so you'd have to provide /U and /P values.