关于phpexcel有关问题

关于phpexcel问题
在本地运行。导出excel都没问题，但是部署到服务器上就没反应了，看了网上类似注销//require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/ZipStreamWrapper.php';也没作用，以下是导出代码，各位大神谢谢给出意见：

//excel导出
function excel(){
require_once './Classes/PHPExcel.php';
require_once './Classes/PHPExcel/IOFactory.php';
$u = D('clients');
$data=$_SESSION['datas'];

$objPHPExcel = new PHPExcel();
// Set properties
$objPHPExcel->getProperties()->setCreator("ctos")
->setLastModifiedBy("ctos")
->setTitle("Office 2007 XLSX Test Document")
->setSubject("Office 2007 XLSX Test Document")
->setDescription("Test document for Office 2007 XLSX, generated using PHP classes.")
->setKeywords("office 2007 openxml php")
->setCategory("Test result file");

//set width
$objPHPExcel->getActiveSheet()->getColumnDimension('A')->setWidth(8);
$objPHPExcel->getActiveSheet()->getColumnDimension('B')->setWidth(10);
$objPHPExcel->getActiveSheet()->getColumnDimension('C')->setWidth(25);
$objPHPExcel->getActiveSheet()->getColumnDimension('D')->setWidth(12);
$objPHPExcel->getActiveSheet()->getColumnDimension('E')->setWidth(50);
$objPHPExcel->getActiveSheet()->getColumnDimension('F')->setWidth(10);
$objPHPExcel->getActiveSheet()->getColumnDimension('G')->setWidth(12);
$objPHPExcel->getActiveSheet()->getColumnDimension('H')->setWidth(12);
$objPHPExcel->getActiveSheet()->getColumnDimension('I')->setWidth(12);
$objPHPExcel->getActiveSheet()->getColumnDimension('J')->setWidth(30);

//设置行高度
$objPHPExcel->getActiveSheet()->getRowDimension('1')->setRowHeight(22);

$objPHPExcel->getActiveSheet()->getRowDimension('2')->setRowHeight(20);

//set font size bold
$objPHPExcel->getActiveSheet()->getDefaultStyle()->getFont()->setSize(10);
$objPHPExcel->getActiveSheet()->getStyle('A2:J2')->getFont()->setBold(true);