PHP og XML

<?php

$link = mysql_connect("localhost", "user", "passs");
mysql_select_db("database");

$query =  'SELECT * FROM jos_categories';
$results = mysql_query($query);

echo "<?xml version=\"1.0\"?>\n";
echo "<products>\n";

while($line = mysql_fetch_assoc($results)) {
    echo "<item>" . $line["title"] . "</item>\n";
   
    }

echo "</products>\n";

mysql_close($link);

?>

Får den fejl, som jeg ikke kan forstå:

Warning: mysql_fetch_assoc(): supplied argument is not a valid MySQL result resource in /usr/home/web/web80959/test.php on line 12