Ng-enter ddidn't applicate on my items

Hi to everyone, i'm new at Ionic. I'm trying to implement some nice animation in my app. I followed this guide:

http://gonehybrid.com/how-to-animate-your-ionic-app-with-animate-css-and-nganimate/

but when i tried the part with the ng-enter class and the stagger, it doesn't work. If i don't use the ng-enter, all animation work great. My code is the same of the example. I really don't know why that happen!