I would agree with the other posters - ensure the bulbs are planted
deeply enough. How deep? Well they say three to four times the depth
of the bulb, - so 8in/20cm not uncommon, could even be slightly deeper.
The worst thing is shallow planting, the bulbs don't mature, infact
they tend to divide into lots of smaller bulbs.
As the flower is formed inside the bulb this year for next, I would
also water the plant with a tomato fertiliser, fornightly so that it
will build up its reserves whilst in the green. Stop the feed when its
leaves start to fade.
The one thing that you can be sure of, they will come into flower if
the soil is suitable and they are at the right depth.
Good luck.
Clifford
Bawtry, Doncaster, South Yorkshire