If you have problems getting your dough to stick together, this is usually due to the wrong ratio of butter vs flour. To be certain you have the right ratio, you need to weight the ingredients. It can also be due to using butter with too low fat content. Your butte r should have at least 80% fat. First step to solve this, is to keep working the dough with your hands. It can take a while for everything to come together well. Second step is to add 1-2 tablespoons more of butter and see if that helps. Don't add too much though, or the cookies will end up flat.