Notification Center

Okay, so whenever i get a snapchat it will show up in the notification center, as usual. Once i click on it, it usually goes away, but recently they wont automatically clear like they usually do once i go into the app and look at the snaps. It's getting very annoying to have to constantly hit clear for those notifications all the time. Does anyone know how to get it to stop?? or work properly again I should say