Someone ate my bulbs!
After digging up one bulb and realizing it was rotton I decided to dig up another plot of bulbs that haven't done anything. I think it is a butterfly plant of some sorts. I went to town, I found my tulips but the butterfly bulbs were nowhere to be found. I dug and dug, and sifted through the soil and still nothing. I'm guessing they have either rotted away or vole got to them. I did find a dead one in the yard a few weeks ago, a present left behind by one of the strays in the neighborhood. There is always next year.
I would be inclined to blame rot, unless you have seen evidence of vole burrows in your yard. I remember you mentioning in an earlier post that your soil is heavy clay, and to plant your bulbs, you dug a deep trench and filled it with good soil. As I suggested in my response to that post, that method of planting can actually create a "dry well" effect in heavy soils, allowing water from surrounding areas to drain into the newly planted area. I have heavy clay soil in my yard, and I learned that lesson by experience. I killed a lovely, mature tree when I dug a deep hole under it to bury one of my large dogs that had died. 
It's just one of those things that, as the saying goes, "looks good on paper," but doesn't work very well in practice.
Do try again next year, but consider planting your bulbs in a very shallow trench, then piling soil on top, perhaps creating a berm type of effect. Another method is to outline the planting areas with some type of decorative edging, then filling in with good soil. I have even successfully planted bulbs by just setting them on the surface of the soil and mounding more soil over them. There's almost always a solution, so don't give up.
It's just one of those things that, as the saying goes, "looks good on paper," but doesn't work very well in practice.
Do try again next year, but consider planting your bulbs in a very shallow trench, then piling soil on top, perhaps creating a berm type of effect. Another method is to outline the planting areas with some type of decorative edging, then filling in with good soil. I have even successfully planted bulbs by just setting them on the surface of the soil and mounding more soil over them. There's almost always a solution, so don't give up.