Not sure if I am just losing my mind, but I can not figure out how to ventilate a roof. Before anyone asks, I have read the mod guides. I install the DVFD Ladder and/or the ground ladder to the roof and send a firefighter up with a full SCBA tank and a K-12 equipped. I have moved him around the entire rough to find a spot to cut but when I hit "vent roof," it says not available at this time. Any help on this would be great.