header() issues

I'm having some problems with forced download headers. I send the $Version and $Format variables via a form to this script listed below. The download starts but it has no file extension, nor is the content correct. The file is always named something wierd like cce416ec or 4902c2c9 depending on which $Format I choose in my submitted form. I have pretty much the same Version and Format scheme setup to feed the same files to a php mail class as a file attachment, and that works just fine. I just can't get these download headers to work right though. <? if($Format == "Unix"){ $ext = ".tar.gz"; $content_type = "application/x-gzip"; } if ($Format == "Windows"){ $ext = ".zip"; $content_type = "application/x-zip-compressed"; } $filename = "/home/src/file_v$Version$ext"; $short_filename = "file_v".$Version.$ext; header("Content-Type: $content_type; name=$short_filename"); header("Content-Transfer-Encoding: binary"); header("Content-Disposition: attachment; filename=$filename"); ?> I've been looking through php mail archives all day. There are so many different opinions about how to do this, but none work for me. Any suggestions? Thanks, Greg