function add_event_register(eid) {
  Event.observe(window, 'load', function(){
    var form_id = 'event_register_' + eid; 

    Event.observe(form_id, 'submit',(function(event){
      new Ajax.Updater('event_register_result_' + eid, '/event/' + eid ,{
        evalScripts:true, 
        onComplete:function(transport){
          Form.enable(form_id);
          Element.hide('search_spinner_' + eid);
        },
        onSuccess:function(transport){
          Element.hide(form_id);
          Element.removeClassName('event_register_result_' + eid, 'error');
          Element.addClassName('event_register_result_' + eid, 'success');
          Element.show('event_register_result_' + eid);
        },
        onFailure:function(transport){
          Element.removeClassName('event_register_result_' + eid, 'success');
          Element.addClassName('event_register_result_' + eid, 'error');
          Element.show('event_register_result_' + eid);
        },
        method: 'post', 
        onLoading:function(transport){
          Element.show('search_spinner_' + eid);
          Form.disable(form_id);
        }, 
        parameters:Form.serialize(form_id)
      });
      Event.stop(event);
    }).bindAsEventListener(), false);
  }, false);
};