我的ajax_framework代码有什么问题？

Question

When I use action="updatebonpen.php" directly in the html page, it updates the database well. Now, I tried using jQuery to update my database, it'll just keep showing "Adding, please wait..." without updating the database.

I have used this same codes in another site earlier and it is working very fine there. Below is the code:

/* ---------------------------- */
/* XMLHTTPRequest Enable */
/* ---------------------------- */
function createObject() {
  var request_type;
  var browser = navigator.appName;
  if(browser == "Microsoft Internet Explorer"){
    request_type = new ActiveXObject("Microsoft.XMLHTTP");
  }else{
    request_type = new XMLHttpRequest();
  }
  return request_type;
}

var http = createObject();

/* -------------------------- */
/* INSERT */
/* -------------------------- */
/* Required: var nocache is a random number to add to request. This value solve an Internet Explorer cache issue */
var nocache = 0;
function insert() {
  // Optional: Show a waiting message in the layer with ID login_response
  document.getElementById('insert_response').innerHTML = "Adding, please wait..."
  // Required: verify that all fileds is not empty. Use encodeURI() to solve some issues about character encoding.
  var bonpen= encodeURI(document.getElementById('bonpen').value);
  var points= encodeURI(document.getElementById('points').value);
  var reason= encodeURI(document.getElementById('reason').value);
  var comment = encodeURI(document.getElementById('comment').value);
  var username = encodeURI(document.getElementById('username').value);
  // Set te random number to add to URL request
  nocache = Math.random();
  // Pass the login variables like URL variable
  http.open('get', 'updatebonpen.php?bonpen=' +bonpen+'&points=' +points+'&reason=' +reason+'&comment=' +comment+'&username=' +username+'&nocache = '+nocache);
  http.onreadystatechange = insertReply;
  http.send(null);
}
function insertReply() {
  if(http.readyState == 4){
    var response = http.responseText;
    // else if login is ok show a message: "Site added+ site URL".
    document.getElementById('insert_response').innerHTML = 'Ok.'+response;
  }
}