comment_node_page_additions and ESI/AJAX [SOLVED]

Hi there,
I'm loading the comment section with this function "comment_node_page_additions()" and i'm including the result in the page with esi and varnish (would be the same if loaded with ajax).

I'm attaching behaviour for the "answer" button but i cant get the submit works.

i've added in the page the drupal ajax library and at the load i execute this code for adding the objects:

jQuery.extend(Drupal.settings, {
    "ajax": {
        "edit-submit": {
            "callback": "ajax_comments_submit_js",
            "wrapper": "comment-form",
            "method": "replaceWith",
            "effect": "fade",
            "event": "mousedown",
            "keypress": true,
            "prevent": "click",
            "url": "\/system\/ajax",
            "submit": {
                "_triggering_element_name": "op",
                "_triggering_element_value": "Salva"
            }
        }
    }
});
Drupal.attachBehaviors("input#edit-submit");

but i get this error:

An error occurred while attempting to process /system/ajax: ajax.form.ajaxSubmit is not a function

how can i deal with this and get the comments area workign correctly?

Thanks best regards.

[SOLVED]
Solved by adding the jquery.form.js plugin and editing a bit the module yo.