jquery disable form submit on enter

I have the following javascript in my page which does not seem to be working.

$('form').bind("keypress", function(e) {
  if (e.keyCode == 13) {               
    e.preventDefault();
    return false;
  }
});

I’d like to disable submitting the form on enter, or better yet, to call my ajax form submit. Either solution is acceptable but the code I’m including above does not prevent the form from submitting.