In reference to James' comment about fertilizing at the right time to initiate flowering. In all honesty, outside of agreeing with a lower N in relation to PK, the timing doesnt really matter as much if you have enough sun light & a good temp drop from day to night. I have many catts that flower immediately as the pseudobulb has develop and leaf fully formed and I have some that develop and several weeks later push out buds. I also have just experienced new lead mature, bloom, and fade and then send up a new lead and then now that this new lead has matured and leaf fully grown the old lead preceding the recently bloomed PB is pushing up a sheath with buds. What I gather is that any PB that hasn't flowered or had new developing buds rot in a sheath or suffer rot in general can flower at any point on a regular one to two times a week fertilizer schedule. So as for having to fertilize at just the right time may not always hold as a steadfast method.
This is a very pleasing thought to say the least in any case.
Don't give up on those non-blooming leads just yet!