I have some lovely standard impatiens in indoor containers that a friend gave me (I do not know the exact species). I keep the soil evenly moist (not soggy), with good drainage, and water only when the very top of the soil gets sandy. There are some beautiful buds on it on the verge of blooming, yet they will not open, nor are the buds just dropping off. I had the plants last year at this time and there wasn't the same problem. Any ideas?