Hi, Well unless they are Species tulips, most tulip varieties only bloom reliably for a year or two and then stop. That's why, in Holland, they replant every year. Only the species types come back year after year. Also, it might reflect how they were treated the year before when they were growing. After a bulb flowers you need to leave the foliage intact until it completely turns brown and dies back. This allows the plant to build up energy for the following year. It also helps to deadhead (remove the faded flowers) from tulips.