How do i connect with my boyfriend's daughter?

Since I've been with my boyfriend, I have always do everything to connect with his kids. He has a girl 14 and a boy 7. I connect well with the youngest but for the girl I feel like unless I give her money or buy her something I will never connect with her. Every time I plan for us but(me, her, my bf and the son) she always say "I don't wanna hang out with my Dad, I want to hang out with my friends" What do I connect with her?