[FirstYorkie]

It's quite common at that age. First, just get him used to the harness. Put it on, then feed him or give him treats. Tell him how beautiful he looks, then take it off. Repeat numberous times until he seems comfortable with it.

Then, attach a leash and just let him drag it around. Use the above treatment until he gets used to it. Only once he's comfortable with dragging the leash should you try to pick up the other end.

Have fun!