If your chapter is using PayPal to process your online payments with Event Espresso, your current gateway has become deprecated. While the payment process still works, the callback to your dashboard to record the completed transaction does not. This means that even though your attendees have paid, it is not indicated as such in your chapter dashboard.
To fix the issue, chapters must contact ASSP's chapter web services team to complete the update. You will need your PayPal account username and password along with access to the two-step authentication device if you enabled that security feature.