Content-Length header always zero

I set a header in the following way: ``` header('Content-Length: ' . filesize($strPath)); ``` On my PC with ZendServer it works fine and I can download a file with the correct file size. On the production server, a Solaris with Apache and compiled PHP, I get a file with the file size equal to zero, so an empty file. Is there a config parameter? Something that can prevent to set 'Content-Length: 1222'? Thanks. The code: ``` <?php error_reporting(E_ALL); ini_set('display_errors', '1'); require 'includes/prepend.inc.php'; require __ADMIN_DIR__.'/AdminInfo.php'; $intFile = QApplication::QueryString('fileID'); if($intFile == '') die('Error: missing ID'); $objFile = File::Load($intFile); $blnRight = false; $objAdminInfo = new AdminInfo(); if($objAdminInfo->isAdmin()) { $blnRight = true; } else { $objSecMan = new SecurityManager( 'file:'.$objFile->FileID, $objAdminInfo->getUserID() ); $blnRight = $objSecMan->processResource('view'); } // if the user can modify and or publish, can even view the file if(!$blnRight) { $blnRight = $objSecMan->processResource('modify'); if(!$blnRight) { $blnRight = $objSecMan->processResource('publish'); } } //$strPath = __UPLOADS__.DIRECTORY_SEPARATOR.$objFile->FileID; $strPath = 'subdept.csv'; if (file_exists($strPath) && $blnRight) { header('Content-Description: File Transfer'); header('Content-Type: application/octet-stream'); header('Content-Disposition: attachment; filename='.$strPath);//$objFile->Filename); header('Content-Transfer-Encoding: binary'); header('Expires: 0'); header('Cache-Control: must-revalidate, post-check=0, pre-check=0'); header('Pragma: public'); header('Content-Length: ' . filesize($strPath)); ob_clean(); flush(); readfile($strPath); exit; } else { die('Restricted access'); } ?> ``` When I comment the code before $strPath it works, so it must be something in the bloody framework. I would like to throw the whole CMS away.