t:commandButton action method not called

[Le Van]

Hi all,  I got a problem with t:commandButton. I have Search screen. First, I push Search button to get data from DB. Then I push OutputCSV button to get data results as csv file. Everything is OK.Now I push search again, but action is not been called for all command button on the screen ( except h:commandLink can take an action). Here is my code to get data as csv. public String outputCSVAction() {                         FacesContext facesContext = FacesContext.getCurrentInstance();                 HttpServletResponse response = (HttpServletResponse) facesContext.getExternalContext().getResponse();                 ByteArrayOutputStream arrayOutputStream = new ByteArrayOutputStream();                 List dataList = pageObject.getDataList();                 for (Iterator iter = dataList.iterator(); iter.hasNext();) {                     TM00403ItemRow element = (TM00403ItemRow) iter.next();                     prepareCSV(element, arrayOutputStream);                 }                 response.setContentType("application/x-download; charset=shift_jis");                 response.setHeader("Content-disposition","attachment; filename=\"" + TMCommonConstants.OUTPUT_CSV + "\"");                 ServletOutputStream outputStream = response.getOutputStream();                 outputStream.write(arrayOutputStream.toByteArray());                 response.setContentLength(arrayOutputStream.size());                 outputStream.flush();                 outputStream.close();                                facesContext.responseComplete();              }   Could anyone help me ?   Thanks for advance,   Van Le