how to communicate actionscript3.0 with php? - php

Question

i am trying to send the data from actionscript to php file.but am not able to communicate with php file.am getting error like this "Undefined index: username in C:\xampp\htdocs\As\basics.php on line 2".
my code is below.
/*********actionscript******************/
var str:String = "hi";
var myscore = 0;
submit.addEventListener(MouseEvent.CLICK, fl_ClickToGoToAndStopAtFrame_7);
function fl_ClickToGoToAndStopAtFrame_7(event: MouseEvent): void {
var myrequest:URLRequest = new URLRequest("http://localhost/As/basics.php");
myrequest.method = URLRequestMethod.POST;
var variables:URLVariables = new URLVariables();
variables.username = str;
variables.score = myscore;
myrequest.data = variables;
var loader:URLLoader = new URLLoader();
loader.dataFormat = URLLoaderDataFormat.VARIABLES;
loader.addEventListener(Event.COMPLETE, dataOnLoad);
loader.load(myrequest);
}
function dataOnLoad(evt:Event)
{
submit.alpha=100;
//status is a custom flag passed from back-end
}
/*********php code**********************/
<?php
$name = $_POST['username'];
echo "Result:<input type='text' value='$name'>";
echo "<param name='movie' value='cmphp.swf' />";
echo "<object type='application/x-shockwave-flash' data='cmphp.swf'width='1024' height='500'>";
echo "<param name='movie' value='FlashVars_AS2.swf' />";
?>