Mine are the same. If yours have been in for a few years, then wait until they're dormant, and dig them up. Discard the old corms and re-plant the newer ones. You can also split clumps - not easily, but I did last year and they're flowering much better. If they're new ones, then be patient, let them mature. I planted new ones last autumn, and they haven't flowered. I'll have to be patient too!