Write XML to local file PROBLEM!

[flashforarmy]

I'm trying to write XML to a local file using PHP or ASP. It seems to work but the file never shows up. Am I missing something with the permsissions? Please help. Here's the details:

Flash 8

on (release) {
// A. Construct a XML document with a LOGIN element
loginXML = new XML();
loginElement = loginXML.createElement("LOGIN");
loginElement.attributes.username = "MyDog";
loginElement.attributes.password = "barkbark";
loginXML.appendChild(loginElement);
loginXML.contentType = "text/xml";

// B. Construct a XML object to hold the server's reply
loginReplyXML = new XML();
loginReplyXML.onLoad = onLoginReply;

// C. Send the LOGIN element to the server,
//place the reply in loginReplyXML
loginXML.sendAndLoad("save3.php", loginReplyXML);

PHP

<?
$filename = "xmloutput.txt";
$fp = fopen( $filename,"w+");
fwrite ( $fp, "$HTTP_RAW_POST_DATA" );
fclose( $fp );
print '<?xml version="1.0"?><result>LOGIN OK</RESULT>';
?>