I believe your problem is with the mysql server name. That sould be something like mysql.example.com. You'll also need to specify the database name, plus user/pass.
In the Panel click Goodies >Manage MySQL> and find the "hostname" for the database(s) you're trying to backup. The bold text under "Database" is the name of your DB.
Hopefully you can plug in this information and get your software working. There's also an article in the DH wiki title Automatic Backup that you may find helpful - not only does it cover backing up MySQL, but site data as well.
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