my code is simple.

```
function useXMLHttpRequest() {
var xmlhttp = new XMLHttpRequest();
xmlhttp.open("POST", "test.ashx", false);
xmlhttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded;charset=UTF-8");
xmlhttp.onReadyStateChange = function () {
    alert("ss");
};
xmlhttp.send("i=5");
alert(xmlhttp.responseText);

```

}

when I call useXMLHttpRequest.Yes ,it alerts the xmlhttp.responseText's value. but it doesn't alert("ss"). Both in IE9 and firefox.
Anyone can tell me what's worng?