Error 500.52

After setting up Rewrite Provider from the link below, and the Rule to do the redirect, I am getting an Internal Server Error 500 every time no matter what I use as a URL.

http://www.iis.net/learn/extensions/url-rewrite-module/using-custom-rewrite-providers-with-url-rewrite-module

The error is:

Any help would be greatly appreciated.

Thanks!