What am I doing wrong, sunscreen?

So I took the kids tot he water park today. I had them redo their sunscreen regularly, never going over 1.5 hours even though the bottle said it lasted longer.

I made sure they dried off and I made sure they rubbed it in good and let it sit for a few minutes.

Bub STILL got sunburn on his shoulders!

I'm about to just buy him a rashguard shirt.

    What SPF are you using?
    About Melissa
    Birth: December 31
    On Moms.com since: Mar 3, 2014
    I am a single mom of two fantastic kiddos that I love to pieces. Currently in school working towards my teaching degree. You can find me most days on www.mommathoughts.com when I am not here chit chatting! :)