Sending Files/SSL

Greetings- I'm currently working on a PHP script which passes file data through from the filesystem to the webbrowser. This is used for the purpose of sending files that exist outside the web root. Generally this is a simple process-- opening the file and using the fpassthru command. I have this working correctly. However ,the entire site is now using SSL and the script no longer functions. i.e. http://www.myserver.com/sendfile.php?file=/whatever/whatever.doc works without a problem but once the protocol changes to: https://www.myserver.com/sendfile.php?file=/whatever/whatever.doc it fails. What am I missing that prevents me from allowing this script to work with SSL? Thanks. Regards, Adam Whitehead