Honesty works but with younger girls, high school and such, not so much. I feel like there’s still a process to liking someone and dating and it’s not as forward as just talking to someone. Also if you’re 18 and she’s 15... it could be a little intimidating to her. There are tons of factors, I wouldn’t be concerned, you sound a little too forward but I’m thinking it’s the fact you approached a fifteen year old fresh out of middle school who still holds “crushes” as a big secret, probably, I dunno. I just know there was a significant amount of anything I did from freshman year to senior year and how I handled dates one of those things I matured in.