I need to run on IIS. Why didn't you add an information about not tested on IIS? I need to use this today. I can't send newsletter for 3 days. Please fix my problem.
We have specified that you need a Unix like server, eg. Linux, running Apache.
Taken directly from our website:
You need PHP & mySQL support on a Unix like server, eg. Linux, running Apache.
I have completely no clue what the issue is if I can't see your error logs. Please consult your host on where to retrieve the error log from your server.