Amaryllis bulbs are typically prolific flowering plants producing at least one bloom stalk per bulb each year when supported by good cultivation practices. When amaryllis fail to bloom, it can be for a number of reasons---including too much nitrogen fertilizer, immature or recently dug or divided bulbs, too little sun or poor soil drainage conditions. All of these can be remedied with a few easy fixes and a year's time to recover and recharge the bulb for bloom.
Feed your amaryllis three times each year with a low-nitrogen slow-release complete fertilizer formulation---with a guaranteed analysis such as a 5-10-10 or a 6-12-12. Make the first application in March, the second in June and the third in late August or September to recharge the bulb for the following year's bloom.
Water your amaryllis bulbs so the soil remains lightly moist on a consistent basis but is not consistently wet. When rain has occurred, scale back watering to prevent over saturation of the soil.
Dig and transplant bulbs to a full-sun location when they grow in a shady location and don't bloom every year or every other year.
Refrain from digging, dividing or transplanting your amaryllis bulbs for a few years to allow the bloom cycle to normalize and reestablish itself.