AJAX-Codeigniter

Having gone through all the exisiting questions, I could not find a solution to the problem I was facing.

I have a Codeigniter application, which on one of it's views has a form which makes a AJAX call to submit data.

I have the Jquery code working for two AJAX calls but for one of the calls, from what I monitor in the header returns a resource not found error for the controller I call via POST. If I load the same resource directly, the browser loads the URL.

Here's my code

$(document).ready(function()
{
    $("#submit_tag").click(function(){
        $("#current_tags").fadeOut("fast");
         tag = $("#new_tag").val();

            $.ajax({
                type: "POST",
                data: "data="+tag,
                            //This returns a resource not found error
                         url: "<?php echo site_url('user/updatetag/');?>/",
                success: function(msg)
                {
                $("#current_tags").remove();
                $("#current_tags").fadeIn("fast");
                $("#current_tags").html(msg);

                }
                 });
                   });
    $("a.single_tag").click(function(){
        the_id = $(this).attr('id');

            $.ajax({
                type: "POST",
                data: "data="+the_id,
    //This URL works    url: "<?php echo site_url('user/deletetag/');?>/",
                success: function(msg)
                {
                    $("#current_tags").fadeIn("slow");
                    $("#current_tags").html(msg);

                }
            });

    });

});

Thanks for your time

what is #new_tag, is it input field/text area/select/similar or usual html tag like div?

if its about input/text area/select/similar, then your AJAX/JS is OK. May be problem in CI code.

if its usual html tag, then you should get the value of that tag using .html()-

tag = $("#new_tag").html();

#new_tag is a id of a textfield from which I am reading a value from to be inserted into the database.

All the CI code does is echo "Saved";

from what I see on Firebug, it says that it failed to load the resource.

EDIT :

I resolved the issue, but adding a action to POST="(Code Igniter URL)" to the form tag which was previously missing.