He Doesn't Want to Sext

My boyfriend and I are in a long distance relationship. I have a pretty high sex drive. So since we can't have sex I like to sext. He's great at sexting back in text but whenever we're on Skype he gets so nervous he can barely speak. He's told me he just gets shy and wants to but just gets shy. It's starting to really harm our relationship because I'm young and my sexuality is important to me. I get that he's not going to always want to but he literally cannot do anything on Skype ever and can every day through text. What should I do?