There are a couple local nurserys I have seen "neglect" their plants to stress them into blooming. That is, you stop watering them regularly and you stop fertilizing them. Sometimes the heat/cold changes and the humidity changes can also blast sheaths. I'm a pro at blasting them...it's pretty common and very very annoying. Hang in there, maybe it will bloom nicely in a few more months. One less positive...I have heard of plants that never bloom and forget now what they call them (other than annoying, or cuss words, lol).