Twitter Bootstrap Wizard and jquery.validate

Twitter Bootstrap Wizard and jquery.validate

I need to disable next button on validate my form.

Here is my validate code:
  1.     <script type="text/javascript">
  2.         $(document).ready(function () {
  3.             $('#BereketF :input').blur(function () {
  4.                 $('#BereketF').validate().form();
  5.             });
  6.         });
  7.     </script>
If user missed a input, next button will be disabled.

Next button's class = .next