That entry looks like it is trying to do a hotadd of the disk (preferred method for backup) and it failed to do so.
You should see an entry that shows :
avvcbimage Info <9666>: Available transport modes are file:san:hotadd:nbdssl:nbd (these are listed in order of preference for how the backup will be performed)
Then, search for the word 'Connected' to see if you get entries showing that the VMDK was connected for backup.
If you don't see that, then there should be an error message "Failed to connect" that gives reasons why the connection failed.