php excel multi worksheet

<?php
error_reporting(1);
$fName='tmp/006data.xlsx';
if($_POST)
{

    $aData=$_POST['txt'];
    $sType='2007 XLSX';
    error_reporting(E_ALL);
    date_default_timezone_set('Europe/London');
    require_once 'Classes/PHPExcel.php';
    $objPHPExcel = new PHPExcel();
    $objPHPExcel->getProperties()->setCreator("Nasgor")
     ->setLastModifiedBy("Gunawan")
     ->setTitle("Office  Test Document")
     ->setSubject("Office $sType Test Document")
     ->setDescription("Test document for Office $sType, generated using PHP classes.")
     ->setKeywords("office $sType openxml php")
     ->setCategory("Test result file");


    $ar=array();
    //tab1
    $ar2=
    array(
        1=>array(
            1=>"A1",2=>"B1",3=>"C1",4=>"D1"),
        3=>array(
            1=>"A3",3=>"C3",4=>"D3",5=>"E3")
    );
    $ar2[4][5]="E4";
    $ar[]=$ar2;
    //tab2
    $ar2=
    array(
        1=>array(
            1=>"A1",2=>"B1",3=>"C1",5=>"E1"),
        3=>array(
            1=>"A3",3=>"C3",4=>"D3",5=>"E3")
    );
    $ar2[6][5]="E6";
    $ar[]=$ar2;

    $aName=array('test 1','test 2');
    //=========TAB========
    foreach($ar as $id=>$a1)
    {
        $objWorkSheet = $objPHPExcel->createSheet();
        $objPHPExcel->addSheet($objWorkSheet);
        $objPHPExcel->setActiveSheetIndex($id);
            $sheet = $objPHPExcel->getActiveSheet();
        foreach($a1 as $posY=>$a2)
        {
            foreach($a2 as $posX=>$val)
            {
                $pos=chr(64+$posX).($posY );
                $val?$dt=addslashes($val):$dt='';
                $sheet->setCellValue(  $pos,$dt);
            }

        }

        $objPHPExcel->getActiveSheet()->setTitle($aName[$id]);

    }

    $writeAs='Excel2007';
    $objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, $writeAs);
    $objWriter->save($fName);
    header('location:?stat=open');
    die();
}

if($_GET['stat']=='open')
{
    header('Content-type:application/vnd.openxmlformats-officedocument.spreadsheetml.sheet') ;
    header('Content-Disposition: attachment; filename="'.$fName.'"');
    $f=file_get_contents($fName);
    echo $f;

    die();
}
?>
<form method="post"  enctype='multipart/form-data'>
<input name=stat type=submit value='update' />
</form>