PHPExcel is not exporting some data

I have given var_dump to $row_data and all data is coming, but the problem is when I will generate the data by PHPExcel dynamically.

In a table the data is generated, with no apparent problem. I tested it on another table (most of the answers are in English) and only one row is generated and several columns are missing data as well. I gave var_dump in both ( $row_data ) and the data is all there!

$sql = "SELECT * FROM $tbname WHERE ID<30";


$i = 0;
$rowID = 2;

while($i < count($row_data)) {
    $col= 0;
    foreach($row_data[$i] as $key=>$value) {

        $objPHPExcel->getActiveSheet()->setCellValueByColumnAndRow($col, $rowID, utf8_encode($value));
        $col++;
        echo $value."<BR/>";
    }
    $i++;
    $rowID++;
}


ob_clean();
header('Content-Type: text/html; charset=UTF-8');
header("Content-type: application/octetstream");
header ("Content-Disposition: attachment; filename=\"{$arquivo}\"" );
header ("Content-Description: PHP Generated Data" );

$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel5');
$objWriter->save('php://output');