Sister's first time tasting it

Me and sister have sex for about a year now but every time I try to cum on her face she turns away and I always end cumming on her neck or breasts. She told she might no like the taste, she said might because she never tasted it but by the looks she didn't had the courage to try it. I insisted, and insisted and she finally agreed. By her face on the video she didn't disliked it, the first reaction was better than I expected. She told she thought it would taste much worth than it did.