They don't always survive for me either but, if you plant them all, you will get a couple new plants. I think, sometimes, there's just not enough oomph left in the backbulb to go to all the effort of actually surviving.
I try not to bury the bottom (just whatever roots are still attache, if any) of the bulb, just prop them up with plastic nursery stakes.
I had one backbulb sit for a couple years before it decided to grow. I had gotten it from a friend and couldn't even remember what color it was (turned out it was bright yellow) but, eventually, it grew. If they don't rot, don't give up.
