Should I give up trying?

Okay so there is this girl i like. I am in 10th grade btw. So anyway I met her last year but i didn't really kno her. Midway through the year we started to become friends. Then over the summer we talked all the time on facebook and we text each other a lot. And so we became good friends. So this year started and i have become interested in going out with her. So I started flirting with her and she started flirting back a little. So then i tease her saying i'd ask her to homecoming. She said go ahead maybe she'd she say yes and maybe she wouldn't. this goes on for a while. Then a friend of ours ask her to go with him as friends. She says yes because she doesn't think anyone is gonna ask her to go. So then i ask her out of curiosity " Since your going with (the friend who asked her) and we were just kidding before, i was curious If i had really asked you to homecoming would u have said yes". She said no. So should i just ume she isn't interested and move on or should i keep trying