modalWindow can't be closed

[蔡茂昌]

hi, i have a problem , i have a modalWindow, there is a button in the
modalWindow,when i click the button ,i want the modalWindow be closed ,but
now it can not be be closed , below is my code ,
AjaxButton saveBtn = new AjaxButton("save") {
   @Override
   protected void onSubmit(AjaxRequestTarget target, Form<?> form) {

    List<People> list3 =
peopleService.fetchBySearchCondition(searchCondition);
    List<PeopleForExport> resultList = doTransLate(list3);
    File file = peopleService.exportExcelFile(resultList,formModel);
    IResourceStream is = new FileResourceStream(file);
    try {
     if (((WebRequest) getRequest()).getHttpServletRequest()
       .getHeader("User-Agent").toLowerCase().indexOf(
         "firefox") > 0) {
      getRequestCycle()
        .setRequestTarget(
          new ResourceStreamRequestTarget(is)
            .setFileName(new String(file
              .getName().getBytes(
                "UTF-8"),
              "ISO8859_1")));
     } else {
      getRequestCycle().setRequestTarget(
        new ResourceStreamRequestTarget(is)
          .setFileName(URLEncoder.encode(
            file.getName(), "UTF-8")
            .replace("+", "%20")));
     }
    } catch (UnsupportedEncodingException e) {
     e.printStackTrace();
    }
    getRequestCycle().setRequestTarget(null);
    modalWindow.close(target);
   }
   @Override
   protected void onError(AjaxRequestTarget target, Form<?> form) {
    target.addComponent(feedbackPanel);
   }
  };
  form.add(saveBtn);

thanks

--jans