My sister

I'm 15, she's 9. We're sitting on my mother's bed just laying there. I offer her a massage and start rubbing her back. I lift us her nightgown to reveal her smooth tan back. I rub her back, and then ask if I can rub her legs. She's hesistant at first but says "yes" so I start to rub her legs. I accidenlty tickle her for a lil bit and then offer to massage her butt. She's says okay, and I start rubbing it and tells me to stop. I ask if I can pull her underwear down and do it but she goes like NO!

What should I do /lounge/?