Session lost when make ajax cross sub domain

[huyhoang08]

i have 2 sub domain:<br>
http://abc.vn/s.php<br>
http://t1.abc.vn -> point to /1.php
<p>php script bellow:</p>
**s.php**
<?php
//make session avaiable on all subdomain
session_name('hoang'); //set session name
session_set_cookie_params(0, '/', '.abc.vn');
@session_start();


$_SESSION['a']='A';
?>
<script>

function createCORSRequest(method, url){
var xhr = new XMLHttpRequest();
if ("withCredentials" in xhr){
//xhr.withCredentials = "true";
xhr.open(method, url, true);
} else if (typeof XDomainRequest != "undefined"){
xhr = new XDomainRequest();
xhr.open(method, url);
} else {
xhr = null;
}
return xhr;
}
var request = createCORSRequest("get", "http://t1.abc.vn");
if (request){
//request.setRequestHeader('Origin','*');
request.onload = function(){
alert(request.responseText);
};
request.send();
}
</script>

And:
**1.php**
<?php
//make session avaiable on all subdomain
session_name('hoang'); //set session name
session_set_cookie_params(0, '/', '.abc.vn');
@session_start();

if(isset($_SERVER['HTTP_ORIGIN']))
{
$http_origin = $_SERVER['HTTP_ORIGIN']; //check cros
if (in_array($http_origin,array("(URL address blocked: See forum rules)",'(URL address blocked: See forum rules)://localhost')) )
{
header('Access-Control-Allow-Origin: *');
}
}
print_r($_SESSION);
?>

But when ajax call, i get result Array() in 1.php script.
I try to copy ajax url into browser, but it show me right result.
How? i don't understand. Help me.
I will Thanks for all question.