Events + Plugin

If you go to http://www.eventnj.com and click "I'm attending", click the register link, register for new account (we will delete after), and sign up for FREE membership. Then go back to home page and click "view events."

This brings you to a page which is the event listing and I was able to click I’m attending but did not pay - I see the pay now button on the page - but the problem here is that there needs to be something that tells the person that they have only RSVP’d and not paid - it should be a pop up page or something.

How can we do this? We need to make sure that all RSVP's pay or know they must pay. How can we do this?

Thanks!