Zantedaschia failing to flower
by Vivian
(Wales, United Kingdom)
Doug says that the problem of not flowering means the bulb isn't getting something it wants. Like enough sunshine or fertility (the main two causes) so that it can store enough energy into the bulb to produce a bloom.
It also depends on how large the plant was when you purchased it. If very small from the bargain bin, then they can take a few years to develop the strength to produce a bloom.
This year's bloom depends on what you did last year (for the most part) to produce a strong healthy plant. What you're doing this year will determine the success of next year.
Not knowing how you're feeding etc means I can't give you a good answer but let me suggest you read the sections on this plant and try to make sure it really gets the growing conditions it wants.