Is it getting enough water? That could be a reason.

hello ,I have seven various hibiscus,six of them flower every year the seventh is exactly what you describe,always buds but never gets past the just opening stage, i have moved it three times to different positions but no difference,told this was caused by poor drainage, irregular watering, and thrip infestation, tried all the usual treatments good feeding regime and good watering regime, nothing works,tried organic and non organic treatments how this plant has never died is surprising, but each year it grows exactly the same, full of variegated leaves hundreds of part open buds and then nothing,sorry its not much help but if you ever solve it i would really like to know,this plant is now in its 8th year and still puzzled, even went back to the nurseryman i purchased it from and he could shed no light on it offered to change it but by then i was on a mission, lol.