What should I add to my puppy's food--please read details?

I've been feeding my 6 months old dachshund Pedigree Puppy Formula, but he does wag his tails, get happy, or has a healthy appetite, he just eats because he is hungry, I've tried science diet, purina puppy chow, purina ONE, and Iams, none worked, what should I add to my puppy's food to make it more yummy???