The problem lies with the schedule wich executes the command I believe
I've seen the same error backing up a windows client with a command.
The event log reports completed even if I give the wrong path name for the
command file.
I changed the backup schedule to incremental and tailored the opt file.
With the SQL agent I believe you have to use the schedule with command.

This has not been much help only to confirm your problem has been noticed by
other users.
Can anybody else help with this problem?

Thanks in advance

Leo