I cannot get PopUp to work...at all!

I have installed the latest version of PopUp (4.5.3)

I am using WP 3.9.1

I also have used the latest versions of Firefox, IE, and Chrome

I cannot get even a simple PopUp to display.

What I really want to do is have a popup display depending on a specific referrer. That didn't work.

I then tried a simple popup with no conditions...that didn't work either.

What is going on?

Please help