phpexel и codeigniter получают ошибку

Я получаю все, как описано по этой ссылке: http://www.ahowto.net/php/easily-integrateload-phpexcel-into-codeigniter-framework, но я получил это в своем файле excel (я использовал пример с сайта, где есть учебник): http://img11.imageshack.us/img11/7017/errorfzh.jpg

И мой контроллер:

    class Mail extends CI_Controller {
    public function __construct(){
        parent::__construct();
        $this->load->library(array('form_validation', 'excel'));
        //activate worksheet number 1
        $this->excel->setActiveSheetIndex(0);
        //name the worksheet
        $this->excel->getActiveSheet()->setTitle('test worksheet');
        //set cell A1 content with some text
        $this->excel->getActiveSheet()->setCellValue('A1', 'This is just some text value');
        //change the font size
        $this->excel->getActiveSheet()->getStyle('A1')->getFont()->setSize(20);
        //make the font become bold
        $this->excel->getActiveSheet()->getStyle('A1')->getFont()->setBold(true);
        //merge cell A1 until D1
        $this->excel->getActiveSheet()->mergeCells('A1:D1');
        //set aligment to center for that merged cell (A1 to D1)
        $this->excel->getActiveSheet()->getStyle('A1')->getAlignment()->setHorizontal(PHPExcel_Style_Alignment::HORIZONTAL_CENTER);

        $filename='just_some_random_name.xls'; //save our workbook as this file name
        header('Content-Type: application/vnd.ms-excel'); //mime type
        header('Content-Disposition: attachment;filename="'.$filename.'"'); //tell browser what's the file name
        header('Cache-Control: max-age=0'); //no cache

        //save it to Excel5 format (excel 2003 .XLS file), change this to 'Excel2007' (and adjust the filename extension, also the header mime type)
        //if you want to save it as .XLSX Excel 2007 format
        $objWriter = PHPExcel_IOFactory::createWriter($this->excel, 'Excel5');  
        //force user to download the Excel file without writing it to server's HD
        $objWriter->save('php://output');
    }
}

Спасибо.