You're getting a blank page? Sounds like a suppressed error to me.
Look for commands starting with the @ sign. Make a backup of the original file, then start removing those @ signs one by one until the server puts an error up.
The @ sign basically stops the server from showing any errors. If it's an error that stops the execution of the page, the execution...Well, stops. Resulting in an empty page, which is displayed as a blank white page.
If that doesn't fix it then I dunno whats wrong, but that should, at the very least, get the system to tell you what broke somewhere.