Not able to take backup in Couchbase3.0?

I want to take backup of my entire couchbase database. i used following line to take backup. But im gettign following error

please provide both a source and a backup_dir

Please help me on this.
cbbackup http://HOST:8091 /backups/backup-20120501
-u Administrator -p password
-b default

any news about that bug?
Also happens to me on version 4

Tell me about that, so important thing and no any response about that!

Hi @itssrinadh, @roycouch,

Is this the same issue as Error when try to do backup or are you still having issues running cbbackup command?