Will my snow fountain weeping willow live??

Ok in July I bought a weeping cherry and it died within 2 months. I don't know what happened. I watered it everyday. I took it back and had to exchange it for another tree (they would not give me a cash refund) So I got a snow fountain weeping willow. Apparently its the same kind of tree as I had before, gets about 12 feet tall but has white blooms instead of pink in the spring. Anyway I planted it Saturday (Aug 25th)and I have watered it lots everyday. We live on sand. But the leaves are already wilting and turning brown. Am I over watering it or is it just in shock? Any kind of help or tips will be appreciated. Thanks!