I eat 400 calories a day?

Why are you doing excersise and weights... YOU NEED TO UNDERSTAND THAT IF YOU HAVEN'T GOT CALORIES TO FUEL YOUR BODIE OR THE RIGHT AMINO ACIDS (ATTAIN THEM FROM HIGH PROTEIN FOODS) THAT YOUR NOT GONNA GET MUSCLEY. Think about it... The only logical way to gain weight( Muscle) is to eat more than you burn off... Simples