School drop off

Hello mummies, My 2.5 YO, after attending sch for a year, still cries at drop off. 😢 it’s just at the point of entrance where she is reluctant to go in.. she usually stops crying once she is inside but I observed that she then tend to follow her teacher around. Not quite like other kids who will play with one another. But at pick up, she seems fine though. I have tried many ways to coax her into not crying but failed most of the time. I also felt that she is trying very hard. Sometimes she will promised me she won’t cry to school but eventually still ended up crying. Any advice from fellow mummies here? Thank you!