AndroidAlarmManager.cancel does not working

Question

static Future deleteByPrescIdx({required int prescIdx}) async{

PillAlarm pa = await AlarmSql.selectOneCloseToNowPresc(prescIdx: prescIdx);
MyUtil.showToastLong('prescDelete [1] ${pa.prescIdx} $prescIdx');
if(pa.prescIdx==prescIdx){
  MyUtil.showToastLong('prescDelete [2] ${pa.alarmId}');
  AndroidAlarmManager.cancel(pa.alarmId);
}

//object box delete
final store = await openStore();
final box = store.box<PillAlarm>();
var query = box.query( PillAlarm_.prescIdx.equals(prescIdx)).build();
query.remove();
store.close();

}

Hi, I'm developing alarm app from Flutter to Android alarm manager Package. But even if I delete the registered alarm, the alarm keeps ringing. What should I do? The alarm has not been cleared by various methods and is still ringing at the registered time. Please help me.