I have two Dalmations in our dog run running down the side of my house. The dimensions are about 60' long by 8 feet wide. In addition, they have 10 feet into the backyard that is chainlinked in. They have a 8X6 foot covered area and their houses. The covered area is covered in brick as well and I let them out twice daily, but every day the dogs take craps on the brick that extends into the backyard. I intentionally left the front area of the dog run covered in grass and dirt for them to take their dumps. How can I train them to use the restroom in the dirt and grass area. Any suggestions?