Apparently, my brilliant AJAX application works perfectly on IE and Firefox, and by surprise, it worked on Opera and Safari as well. But... not on Google's Chrome!
And finally, it got fixed today!
In a nut shell, this is the finding:
var req = new XMLHttpRequest();
.... setting of url etc ...
var tagValue = "";
Basically, when you did this and execute the send function, you'll end up getting a status code of 0. And then, you'll start scratching your head because you won't find the http request in your web server as well.
Hope this will help developers that read this post.