ลองทำ ajax login form ปรากฏว่ามันไม่ส่ง request ครับ

<script type="text/javascript">
function login()
{
	var request;
	if(window.XMLHttpRequest)
		{
		request = new XMLHttpRequest();
		}
	else if (window.ActiveXObject)
		{
		request = new ActiveXObject("Microsoft.XMLHTTP");
		}
	else{
		alert("Browser not support");
		return false;
		}
	var x = document.login;
	var username = x.username.value;
	var password = x.password.value;
	if(username==""||password=="")
	{
	alert("ห้ามเว้นช่องว่าง");
	}
	else{
	var url = "login.php?";
	var url += "username="+username;
	var url += "&password="+password;
	var ran = Math.random();
	var url +="&ran="+ran;
	request.onreadystatechange = statechange;
	request.open("GET,"+url+",true");
	request.send(null);
	}
}
function statechange()
{
		var x = document.getElementById("result");
	if(request.readyState==4)
	{
		x.innerHTML=request.responseText;
	}
	else
	{
		x.innerHTML="<img src='indicator.gif'><br /><h3>PLEASE WAIT</h3>";
	}
}
</script>

<div id="loginform">
	<form name="login">
	<input type="text" name="username" />
	<input type="password" name="password" />
	<input type="submit" value="login" OnClick="login()" />
	</form>
		<div id="result"></div>
</div>