Problems in Basic bone tutorial

I followed step by step after the instructions in “Basic Bone Tutorial”. when i finishing attaching the bones to the different arm layers and moving the bones the layers of the arm are not moving together and get separated
what i an doing wrong?

Hard to say what you are doing wrong.
Some educated guesses:

  1. If you have scaled a layer without the putting the bone layer into it, it messes up the transform. Pretty common problem
  2. You created for each layer an separate bone and not a child bone which is why they don’t move together

If those two do not apply for you, please be more specific with your problem,
otherwise it’s very hard to tell what is wrong.