Description:
------------
Attempting to append child/attributes to an existing xml file using post data from an html form. Post data gets passed fine, but it seems the xml file is never opened or loaded.
Since I don't think the file is ever opened, I am unable to (attempt to) write the new data to the file.

Reproduce code:
---------------
processgb.php
<?php
$xml = simplexml_load_file('gbook.xml');
$sxe = new SimpleXMLElement($xml);
$entry=$sxe->addChild('entry');
$entry->addAttribute('date',date("Y-m-d"));
$entry->addChild('name',$_POST["name"]);
$entry->addChild('email',$_POST["email"]);
$entry->addChild('homepage',$_POST["homepage"]);
$entry->addChild('country',$_POST["country"]);
$entry->addChild('comment',$_POST["comment"]);
$result=file_put_contents($sxe,"gbook.xml"); if ($result<1 or result==false): echo 'error writing: '.$result;
endif;
?>

XML structure:
<?xml version="1.0" encoding="utf-8" ?>
<guestbook>
<entry date="">
	<name></name>
	<email></email>
	<homepage></homepage>
	<country></country>
	<comment></comment>
</entry>
</guestbook>

Expected result:
----------------
The new data is added to the xml file.

Actual result:
--------------
PHP Fatal error:  Uncaught exception 'Exception' with message 'String could not be parsed as XML' in /usr/local/apache2/htdocs/ssa/9112001/guestbook/processgb.php:9 Stack trace: #0 /usr/local/apache2/htdocs/ssa/9112001/guestbook/processgb.php(9): SimpleXMLElement->__construct('') #1 {main}   thrown in /usr/local/apache2/htdocs/ssa/9112001/guestbook/processgb.php on line 9