[Eximili]

Hi, i posted previously saying i got a white and purple dendrobium,hopefully someone can identify it, and its also dying for some reason. Im watering it fine, its in the sun, its not getting sunburned, but the flower buds are green, then they shrivel and turn pink, and fall off, i dont understand whats going on. hopefully some pics of this will help.
ps. there is also some very small areas under the leaves that are like black spots, but they are very tiny and will not clean off.