I am new to Zimbra and was just checking to make sure the backups are working. They are not. When I run the immediate in the admin console I receive the error:

Server error encountered Message: Error! Cannot write to target path /opt/zimbra/backup! Error code: CSFE_SVC_ERROR Method: ZaBackupXWizard.prototype.createPath

Permission of the backup folder are:
zimbra@mail:~/backup$ ls -al
total 32
drwxrwxrwx 5 zimbra zimbra 4096 Sep 17 10:44 .
drwxr-xr-x 58 root root 4096 Sep 17 09:15 ..
drwx------ 2 zimbra zimbra 16384 Sep 17 10:27 lost+found
drwxr-x--- 2 zimbra zimbra 4096 Sep 17 10:44 sessions
drwxr-x--- 4 zimbra zimbra 4096 Sep 20 13:27 tmp

he default settings are correct also. Running ubuntu zimbra 7.1.2_GA_3268