I have an Anne Black. Bought it in March of this year and it's now blooming again.
I bought one from Martin Motes this year (a Bartholomew Motes) @ Fairchild orchid show. It had blooms when I bought it, and it bloomed again for me.
I also bought a Nancy Chandler and it produced a spike right after I bought it.
Let's see. I grow mine if full sun and water them daily. I also fertilize constantly. They have grown a lot since I bought them.
I know the imschootiana grows in cooler conditions than other renantheras.
I can't think of anything else that I do.
Good luck and I'm thinking of buying a phillipinensis and a tom thumb.