If your recipe turns out too dry, the likely culprit is natural peanut butter that was too thick from the oil separating, or the protein powder was a whey isolate protein instead of whey concentrate. Whey isolate protein and plant-based protein powders tend to be more "thirsty" and soak up more of the liquid in the recipe. You can try adding one or two more dates or a little bit of water or maple syrup and pulsing the mixture in the food processor until you get a good rolling consistency.