yellowing buds on an Ascocenda

[PNGPhil]

I'm looking for some help on the culture of my Ascocenda.

I bought it in January in the PNG lowlands (sea level) with beautiful flowers, and brought it home here to the highlands (5000ft). It gradually adapted and put out new roots after a couple of months, then in June I saw the first new flower spike emerging. It had about 7 buds on it as it started to grow, I think, but gradually, one after the other, they started to turn yellow, then brown, then black and fall off. I still have three that could turn in to healthy flowers, but the others are all dead or dying. The attached picture shows what it looks like. What do you think is the most likely cause?

I have the plant hanging in a mango tree, where it gets dappled sunlight, and make sure it gets watered every day (not too hard with the tropical showers here).

Thanks for your advice!

Phil