Download .csv file problem

Hi guys,

I'm writing a code to download the csv file from my website. It's work perfect but some time I click on the download button, it didn't pop up to download a CSV file but it's popup to download a .php file. Some time it's doesn't popup anything but it's display the html code on the screen. It's wild, I don't know what is going on.

Is there anyone experienced this problem before.

Here's my header:

  header('Content-Description: File Transfer');
        //header("Content-type: application/csv");
        header("Content-type: application/octet-stream");
        header('Content-Disposition: attachment; filename='.basename($fname));
        header('Expires: 0');
        header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
        header('Pragma: public');
        header('Content-Length: ' . filesize($fname));
        ob_clean();
        flush();
    
        readfile($fname); 

PHP:

Much appreciated your help and ideas.

Cheers.

Nau

 

Could you post more of the php file? Thanks