Needs help !

I bought this plant 3 years ago as a blooming size phal. It's not dead
yet but it's not happy either. The size remains just as when I first saw
it, no new growth no flower yet. I've moved it to s/h and it still looks
sulked. Are there any tricks about this particular species that I've
missed. Any suggestions will be greatly appreciated. In the mean time my
other phals. are doing well and flower nicely.