Why did she ignore my call, Is she mad at me?

I texted this girl telling her i miss her, about 30 min later she calls me and asked what i was doing and i told her im going to go play bball, so she tells me to call her back later. I called her back 2 hours later and she ignored my call on purpose, Why? It's been a day already and i haven't heard from her, is she possibly mad at me? What should I do?