[jQuery] event is fired every other time after using jQuery's sortable plugin

[Jay W]

I have the following code in a page. everything related to sorting is
working well. Each item has a textarea and this textarea has onkeyup
event handler.  This event handler will only fire every other time.
Does anyone know why this is happening? Thanks.

  $('table.pane').each(function(){
    if (this.id) {
      $(this).sortable({items:"tr.tsdnd", update:saveLists});
    }
  });