Database Failed To Backup On…

I’m getting following error while backup DB:
Database Failed To Backup On ‘June 24, 2013 @ 5:46 PM’.

The backup status is: Excellent. You Are Good To Go.
But when I’m checking in Manage Backup DB option, there’s a backup present for the date/time mention above!!! The database size is 124 MB. Now I’m not sure if other backups are perfect and reliable or not.

http://ww.wp.xz.cn/extend/plugins/wp-dbmanager/