Adtrackz Tracking Error

I purchased adtrackz from the original website with 1 installation. And they didn't even respond or help me install anything...

So I followed the instruction and installed it myself, everything went well except when I test my first link, it return me an error page...

http://domain.com/go/go.php?c=google
Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, [email protected] and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.
Apache/2.2.14 (Unix) mod_ssl/2.2.14 OpenSSL/0.9.8e-fips-rhel5 mod_auth_passthrough/2.1 mod_bwlimited/1.4 FrontPage/5.0.2.2635 Server at domain.com Port 80

Does anyone who uses Adtrackz know what's wrong with it??

Thanks in advance guys.