The dough is too dry and not sticking together – sprinkle more water into the bowl and using your hand or a fork, turn the dough so the water distributes evenly. If you find this out when you are ready to roll, don’t worry. Let the dough come to room temperature so it is on the softer side. As you roll, use your hands to patch cracks back together as best you can. Don’t worry about all the “rules” about not touching the dough – sometimes you just have to get your hands in there and make it stick together! Even if you have to place the dough into the pie plate in two halves, you’re fine. Just piece it together and no one will know the difference.