Popup Pro to close on submit button

I use Popup Pro in a page to show some "Terms of Use". Below the terms I added a simple form (just a submit button) so the user has to accept the terms in order the popup to go away.

Problem is that when the user click the Accept button the popup just refreshing instead of closing.

Any help please?

PS. The Form Submit Behavior is set to default: "Refresh Popup or close"