Please note that you need to score twice in a row over the given score to rank up. If you only score once above the given threshold, then you miss it again by a few points but then manage to score above again, you will not be ranked up. You need to have two scores in a row above the target score, one right after the other.
Also, please note that you can't rank up more than twice in 24 hours so if you had already ranked up once that day, you wouldn't have been able to rank up again.