Fix the .htaccess on a simple Adf.ly clone script

I have an [login to view URL] clone script that's freely available however it is currently not working; the problem being the .htaccess. You can see the script in action here: [login to view URL] As you can see, the script does generate the short URL's but fails to actually redirect (see [login to view URL] for the redirection system I'm aiming to achieve). Everything is set up on the PHP side of things and many have managed to get this work but with no .htaccess knowledge, I'm struggling. I'm looking for somebody to take this quick and easy job of taking the login credentials and fixing the script on my current installation. Hope to hear from you soon.