a problem with submitHandler (form validation plugin)

a problem with submitHandler (form validation plugin)

I was trying to make a simple test of the form validation submitHandler option:

  $(document).ready(function(){
    $("#commentForm").validate({
        submitHandler: function(form) {
            alert("hello world");
            return false;
        }
    });
  });

The alert never happens! is there something wrong with my syntax? Please help!