this page shown an xml file and im trying to use simplexml to parse the data out and print it. what am i missing? cause all it does is show a blank page when i run it.

<?php
$url = "http://api.scribd.com/api?method=docs.getList&api_key=2apz5npsqin3cjlbj0s6m";

$xml = new SimpleXMLElement($url,NULL,true);

foreach($xml -> result as $value) {


    echo $value->doc_id."<br/>";
    echo $value->access_key."<br/>";
    echo $value->secret_password."<br/>";
    echo $value->title."<br/>";



}

?>