Aşağıdaki hatayı çözemedim, data.xls yi indiriyor fakat bilinmeyen dosya türü diyor. Problem ne olabilir?

<?php
$download="";
$query=("SELECT * from excel");
$resultdl= mysql_query($query) or die(mysql_error());
$objPHPExcel = new PHPExcel();
$objPHPExcel->setActiveSheetIndex(0);
// Create a first sheet, representing sales data
$objPHPExcel->setActiveSheetIndex(0);
$objPHPExcel->getActiveSheet()->setCellValue('A1', 'ID');
$objPHPExcel->getActiveSheet()->setCellValue('B1', 'Adı');
$objPHPExcel->getActiveSheet()->setCellValue('C1', 'Soyadı');
$objPHPExcel->getActiveSheet()->setCellValue('D1', 'Telefon');
$objPHPExcel->getActiveSheet()->setCellValue('E1', 'Mail');
$objPHPExcel->getActiveSheet()->setCellValue('F1', 'Adres');
$objPHPExcel->getActiveSheet()->setCellValue('G1', 'Sehir');

$rowcount=2;
while($row = mysql_fetch_array($resultdl)){
     $objPHPExcel->getActiveSheet()->SetCellValue('A'.$rowcount, $row['id']);
     $objPHPExcel->getActiveSheet()->SetCellValue('B'.$rowcount, $row['adi']); 
     $objPHPExcel->getActiveSheet()->SetCellValue('C'.$rowcount, $row['soyadi']);
     $objPHPExcel->getActiveSheet()->SetCellValue('D'.$rowcount, $row['telefon']); 
     $objPHPExcel->getActiveSheet()->SetCellValue('E'.$rowcount, $row['mail']); 
     $objPHPExcel->getActiveSheet()->SetCellValue('F'.$rowcount, $row['adres']); 
     $objPHPExcel->getActiveSheet()->SetCellValue('G'.$rowcount, $row['sehir']); 	 	 
$rowcount++; 
} 
/*
$objWriter = new PHPExcel_Writer_Excel2007($objPHPExcel); 
header('Content-type: application/vnd.ms-excel');
header('Content-Disposition: attachment; filename="excel.xls"');
$objWriter->save('php://output'); die;*/

header('Content-Type: application/vnd.ms-excel');
header('Content-Disposition: attachment;filename="data.xls"');
header('Cache-Control: max-age=0');
$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel5');
$objWriter->save('php://output');
?>