I'm testing the selectpicker plugin of bootstrap like this:
HTML
<select class="selectpicker form-control" id="preffrom">
  <optgroup label="北海道" class="area-hokkaido">
    <option id="p01">北海道</option>
  </optgroup>
  <optgroup label="東北" class="area-tohoku">
    <option id="p02">青森県</option>
    <option id="p03">岩手県</option>
    ...
    <option id="p07">福島県</option>
  </optgroup>
  ...
  <optgroup label="沖縄" class="area-okinawa">
    <option id="p47">沖縄県</option>
  </optgroup>
</select>
JavaScript
$(function(){
  $('.selectpicker').selectpicker();
  // this event is for test  but it does not work...
  $('#test').bind('click', function(e){
    $('#preffrom').val('p03');
    $('#preffrom').selectpicker('refresh');
  });
});
I referenced this: How to set selected value on select using selectpicker plugin from bootstrap
But nothing happens.
Please tell me correct way to select an option using id value.