Undecided Question

Why does my sister doesnt care that she has chapped lips?

She is 11 years old and has really chapped lips. she always has. I put chap-stick on 20 times plus and mine are smooth and perfect. She has blixtex, carmax, chap-stick brand, you name it. She does not put it on! I tell her to put it on or that her lips look chapped but she just stares at me rudely. It looks uncomfortable. Worst part is that she take a million pictures of herself and her lips ruin the picture. You can see the dead skin! Nasty..What should I do?