I don't have this and haven't bloomed the two other speices I have either, however a couple things come to mind. Check this web site
IOSPE PHOTOS There are three environmental issues discussed there that may, or may not, be the culprit. First heat. Apparently it loves very warm temps. Can you provide this? Second, winter rest. Are you drying the plant slightly during winter (resting it)? Third light. I suspected this because lots of other spp in this genera are high ligh plants. Michigan natural light is no-where near strong enough most days to do the trick. I use 3 compact florescent bulbs to supplement natural sunlight in winter - not that we get much of that