Oncidium spikes didn't produce buds

[Sheryl]

i have an Oncidium (not sure of name but it's yellow just like the one on the front page). I've had it many years with many spikes and delightful dancing lady blooms. Once in a while, it'll put out a spike but no buds. I actually have 4 spikes right now with no buds. Any ideas as to why? It grows in my tree and has been there 18 years.

[zainal abidin]

That is the most interesting ? I also have similar condition with Phal like sanderana, schilleriana they keep producing inflorescence but no bud based on my observation this could be the origin of the plants from the higher altitude which refused to bloom at lowland.
Another factor is light sources which is inadequate + lacking of some trace elements. Well maybe you can cut some of the plant let them establish first in the pot then you can do some experiment especially to the light. Its slow process.