IE not passing over success function in AJAXFORM

I have written this ajaxform function with a success function which is being called on sumiting the form. The ajaxform works AWESOMELY in any browser other than IE. I can´t understand why IE is not passing the function.

AjaxForm:

function setupAjaxForm(form_class, updateStatus){
            var form = '.'+form_class;
            var form_action = $(form).attr('action');
            var form_url = form_action+"ajax/";

            var submitOptions = {
                    url : form_url,
                    type : 'POST',
                    dataType : 'json',
                    success : function(json) {
                    var results = json.results;
                              alert(results);
                    if(results == "success"){
                        updateStatus(json);
                    }else{
                        alert(" FAIL ");
                                    }
                    }
            };
            $(form).ajaxForm(submitOptions);
        }

Success function:

function addProductCartStatus(json){
    alert(" Entered for jquery ");
}

Calling function

$(document).ready(function(){
    $('.addto_cart').click(function(){new setupAjaxForm('add_cartForm',addProductCartStatus);});
});

this answer goes mainly to your latest comment

internet explorer is more stiff in some cases. this line result = "success" as mentioned is wrong and converts result into a string with the word success in it and is always true so it always updates

also its recommended to add a error:function(){} on your ajax call