Flash - PHP

var2.load(“http://www.trpsearchit.com/test/1/up.php?uname=u&pword=p&login=1&testvar=1",0,"POST”);
trace(var2.returnvar);

Why is this coming up “undefined”?
I dont understand, here is my php code too

<?
require(‘txtauth.php’);
?>
<?php
if($testvar==1){
echo(“returnvar=test”);
}
?>

It works fine if you type it in the browser, but for Flash it comes up undefined???