start very simple. On the page that you are calling, just echo "hello world" and start there. If that doesn't work then post your ajax function(s). Otherwise, post the code on the page that you are calling and you ajax function(s).
first i call the comment page where comment form is designed, then on submit button another page will be called this is submit_comment.php, then on submit_comment, i want to load another function .. see the example i am doing here: