Help me.about connection between php,mysql and flash

onload function don’t work properly,it didn’t return anything after the php files is executed and the data is inserted into mysql databases.why?
here is my source:
action script

var userData=new LoadVars();
submit.onRelease=function(){
userData.username=username.text;
userData.password=password.text;
userData.email=email.text;
userData.comments=comments.text;
userData.sendAndLoad(“http://localhost/nick/register2.php",userData,"POST”);
}
userData.onLoad=function(){
if(userData.register==“ture”){
gotoAndPlay(“success”);
}else{
gotoAndPlay(“fail”);
}
}

php

<?php
$username=$HTTP_POST_VARS[“username”];
$password=$HTTP_POST_VARS[“password”];
$email=$HTTP_POST_VARS[“email”];
$comments=$HTTP_POST_VARS[‘comments’];

$conn=mysql_connect(‘localhost’,‘root’,‘’) or die(mysql_error());
$db=mysql_select_db(‘test’,$conn) or die(mysql_error());
$result=mysql_query(“INSERT INTO nick(username,password,email,comments)values(‘$username’,‘$password’,‘$email’,‘$comments’)”) or die(mysql_error());
if($result)
{
echo “register=ture”;
}else{
echo “register=fail”;
mysql_close($conn);
}
?>