Did your tree come with a burlap wrapper? Was the tree already leafed out? Was the tree in a fiber pot? Dogwoods are very sensitive to root trauma and transplant shock. It is advisable to plant them when they are dormant and not disturb the burlap or peat pot, whichever it came in. It might be that your sandy soil is not staying damp enough. When you say you watered every day, did you let the water soak down for awhile? The entire root ball plus the soil below it needs to be damp. In my sandy soil, that could take 1/2 hr. of watering with a hose running slowly.
Don't dig it up but do make sure the soil stays damp down into the root zone.