Drobocopy incomplete

I’m new to Drobo FS. I had mine delivered last week and set it up to backup my iMac. On the Mac I repaired all permissions and ran all maintenance scripts. Then I ran Drobocopy. When it finished I got an error msg: Errors:
/Volumes/DroboFS/0db102570480/1/Public/Library/Preferences/com.apple.mail.plist_heraldbackup – Couldn’t create . I am doing something wrong but what? Any help would be appreciated.