Wolfberries Dying

I have bought these from you on three different occasions. The first two times they died and the ones I have now (for two years) are just barely hanging on--never grew.
I know I must be doing something terribly wrong, but what? I have them planted on a hill so they can sprawl--in full sun. I have them mulched. I'm thinking of digging them up and potting them for the winter so they will maybe at least grow then start over next spring. Help? Oh. The soil is--just soil. Junipers had been planted in this space for years--until they died out. I added compost when I planted them. I am totally stumped. Help???

I have a suspicion that you are keeping the plants too dry. They like moist, sandy, alkaline soil. Junipers like acid soil, so since they died out the soil may be alkaline now. But I would suggest changing the contour of the bed they are in to put each plant in a sort of well, so that water catches in the wells and directs the water to the wolfberry roots.
If the soil is clay, you will have to dig the plants up and add lots of sharp builder's sand and maybe well-rotted manure to help the moisture content and the drainage.