Parameter error with mysql_real_escape_string

[DLR]

Hi, I have spend a number of frustrated hours trying to see where my error is. I have copied this from the security tutorial (by DanielO), but cannot see where I am making my mistake. Any pointers will be appreciated.

 

The error I get is Warning: mysql_real_escape_string() expects parameter 2 to be resource, string given in C:\wamp\www\sfwebsite\admin\SF201.php on line 93

 

The code for connection to database sfwebsite works elesewhere in the same programme

 

if(!$conn) {
die('connection error');
}

$db_selected = mysql_select_db("sfwebsite",$conn);  // this is line 93

if(! $db_selected) {
die('connection error');
}

$name = mysql_real_escape_string($_SESSION['username'],'$conn');
$sql = "SELECT level FROM sf_admin WHERE username = '$name' ";
$res = mysql_query($sql) or die('Failed to find Admin records');

[trq]

$name = mysql_real_escape_string($_SESSION['username'],$conn);

[DLR]

Thanks. I could kick myself.