Have you checked to see how deep it is planted? Often, that's something to look at as a plant sinks in from it's original planting. The crown ( the point where foliage and roots join) should not be set more than 1 inch below the surface of the soil. If it hasn't been divided in years, that can also really affect bloom production. I try to divide every 3-5 years, I generally cut them right in half.
Also, if it's planted in too much shade, that can affect it. They require a minimum of 6 hrs sun.
Water is also essential for good daylily performance. It is most important in spring when the plants are making scapes and buds, and in the summer during the bloom season.
