If your dough is breaking when it is rolled or stretched it is a sign that the dough has been overworked and needs to rest. Let the dough relax, and be covered on the counter for at least 10-30 minutes before trying to roll it out. This happened because the proteins have tightened up during the kneading which is great for creating structure, but not so good for shaping the dough. Letting the glutens relax will make the process go a lot more smoothly.