The machine was never designed to "crisp" the skin, just cook it. Since the PBC cooks a little higher than most smokers it will cook it quite thoroughly but it isn't hot enough to make skin crackle. So: Decide if you want crisp or well done bite-through skin. Either can be done with a little extra work.
For well done, bite-through chicken skin, rub the outside of the bird with Parkay margarine before the cook. About half way through the cook, take the chicken chunks out and spray them liberally with the spray version of the same magic elixir. Read the label. Better living through chemistry. Makes chicken skin tasty and tender but not crisp at PBC temperatures.
For crisp skin try doing what Smokeasaurus does -- ramp up your oven or a gasser or pellet cooker to 400+ and toss the bird in for ten or fifteen minutes at the finish.
My personal opinion is that the PBC does such a marvelous job of making chicking MEAT taste like manna from heaven that I don't give a big red rat's patootie about the skin
Hub