用PHPExcel计算总和

这是我的代码：

$objPHPExcel = PHPExcel_IOFactory::load("test.xls");

$row = 5; 
$S = $objPHPExcel->getActiveSheet();
while($row_data = mysql_fetch_array($result)){


$S->setCellValueExplicit('B'.$row,$row_data['cn']);
$S->setCellValueExplicit('C'.$row,$row_data['ld']);
$S->setCellValueExplicit('D'.$row,$row_data['cust_notify']);
$S->setCellValueExplicit('E'.$row,$row_data['code']);
$S->setCellValueExplicit('F'.$row,$row_data['company_name']);
$S->setCellValueExplicit('G'.$row,$row_data['rs']);
$S->setCellValueExplicit('H'.$row,$row_data['status']);
$S->setCellValueExplicit('I'.$row,$row_data['sueend']);
$S->setCellValueExplicit('J'.$row,$row_data['vclaimed']);
$S->setCellValueExplicit('K'.$row,$row_data['ref']);
$S->setCellValueExplicit('M'.$row,$row_data['out']);

$row++;

$S->setCellValue("I$row","Total");
$S->setCellValue("J$row","=SUM(J5:J".($row-1).")");

}

我得到的结果总是“0”.打印屏幕

如果有人可以帮我解决这个问题,我真的很感激.

提前致谢