>...the script is tasked to back up another Mac running 10.4 with Retropsect Version 6.0...
>Confirm that the remote machine is running Retrospect OS X CLIENT software?
Yes it is.
>Since the message that you document with quotes does not say anything about sync, can you please provide >the exact error message text?
-24161 catalog version is too new - is the exact error message,
What are some of the "various stages" that the backup fails?
As it checks or is it verifies the data on the client, this is before the data has started to copy over.
Hope this helps.