不能从数据库setcellvalue但静态值工作？

I am using this code to set cellvalue from database but it does not work.

    $excel2 = PHPExcel_IOFactory::createReader('Excel2007');
    $excel2 = $excel2->load("test.xlsx"); // Empty Sheet


    $excel2->getActiveSheet()->setCellValue('A1', 'Date');

    $m=2;
    $result=mysqli_query($con,"select * from settings");

    while($row=mysqli_fetch_array($result))
    {
      $chan=$row['channelID'];
                $excel2->getActiveSheet()->setCellValue("C$m", $chan);
    echo $chan;
    echo "<br>";
    $m++;
    }

But when I change this line to static text it works fine

 $excel2->getActiveSheet()->setCellValue("C$m", "static text");

I don't know where I am doing wrong I want to set value from the database any help would be appreciated.