php - MySQL access denied error but everything is correct!

Here's my code

$host = 'localhost';
$username = 'sam_sam';
$password = '[censored]';
$name = 'sam_ballpointradio';

mysql_connect($host, $db_username, $db_password)
or die(mysql_error());
mysql_select_db($db_name) or die(mysql_error());
?>

and the error message is

Warning: mysql_connect() [function.mysql-connect]: Access denied for user 'sam'@'localhost' (using password: NO) in /home/sam/public_html/ballpointradio/db_config.php on line 6
Access denied for user 'sam'@'localhost' (using password: NO)

I know all the information is correct, but it's a weird error because it says I'm NOT using a password, but I am...

Answer

Variable naming problem ?

mysql_connect($host, $username, $password)