backup can't access mysql

[CounterForce]

When I try to backup at the user-level (logged in as admin and then go to user-level) I always get these error when I try to make a backup:

Error while backing up database admin_joom
Error while backing up database admin_joom: The sql file is 0 bytes in size: /home/admin/backups/backup/admin_joom.sql
mysqldump error output: mysqldump: Got error: 2002: Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) when trying to connect

Error while backing up database admin_site
Error while backing up database admin_site: The sql file is 0 bytes in size: /home/admin/backups/backup/admin_site.sql
mysqldump error output: mysqldump: Got error: 2002: Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) when trying to connect

When I make a backup on the admin-level, I don't get the error...

Anyone knows what is happening here?