There are a few possibilities...

My first thought was the alkalinity of your soil. When I lived in Las Vegas, I think the soil there had a pH of 8-8.5.

Are your plants showing any yellowing of the leaves during the growing part of the year? This is usually chlorosis in the desert, caused by high alkalinity (not only in the soil but in the water, too). Do you know the pH of your (unamended) soil? Your local Cooperative Extension Office could probably give you a good idea of what it is likely to be. If it is very alkaline, it might be affecting the bush enough to cause fruiting problems. It's really difficult to acidify alkaline soil enough to grow plants that require acid conditions. Some alkaline soils actively resist being acidified with peat moss, sulfur, etc.

Do any of the bushes flower at all? If they aren't flowering, stop feeding them for a year and see if there is any improvement.

Patriot is one of the earliest blueberries, and if it flowers, are you being hit by hard frosts that are killing the flowers? If so, the PLANT may be hardy enough for the area, but if the frosts are destroying the FLOWERS, it probably isn't a suitable variety for you. Pity, since it's that large.

Is the plant producing flowers that aren't being frozen? Another possible problem is lack of pollination. Even self-pollinatoring plants need bees or other insects to move around and fertilize the flowers.

Did you buy from a reputable company? Was the bush marked with any kind of label that was actually ATTACHED to the bush? Some companies are sloppy about marking and are perfectly capable of sending you the wrong variety.

I would talk to your Ext. Office and see what they think. (see link below)

Sue

Here is a link that might be useful: U.S. Cooperative Extension Offices

My first thought is it probably isn't a blueberry. If it were a pH problem, no blueberry would get 15 ft tall. It would turn yellow with little growth and die.

I won't fiddle with a 15 ft blueberry that won't fruit. Tear it out and try something else.

The Fruitnut

I don't think there is any way Patriot would reach 15' tall. My understanding is it is more in the half-high category, and is supposed to reach a mature height of 4-6'. Rabbiteyes can get that tall, and I have seen wild highbush that tall that did not get enough sun. There are also other Vaccinium species that can get that tall. If you could post a picture, that would really help. Where did you get it? I would look at what other plants the nursery offers that could have gotten mixed up.