[jQuery] jquery validation question: validate a single form element onsubmit

I'm using the validate plugin, and am having a problem with simple one element forms.  I have a single select list and a submit button.  If the select list is empty, the validation prompts that it is required.  When you choose an option, and click Submit, it validates and removes the required message, but then you have to click Submit a second time to actually submit the form... what would I need to do to have it validate the select onchange, so the submit fires the form submit?

validation code:

<script language="Javascript">/* validation for radio button forms */

// wait for the DOM to be loaded 

$(document).ready(function() {

   // validate form on keyup and submit

var validator = $('#select').validate({

      rules: {

field: "required"

      },

      messages: {

field: "Please select a value."

      }

   });

});

</script>

Any advice is appreciated.