FPDF - 仅将文件输出到服务器

I try to save the output of my generated file on my server.

The Code:

$pdf->Output('pdfs/'.$order.'.pdf', 'F');
header("Location: ../email.php");

But when I open the php file in my browser, it still shows the php file with my pdf reader.. Why doesn't this just save the file and redirect me to the email.php?