I tried using the gable roof line tool on a brand new simple four wall plan, and it worked on there, until I changed the main roof pitch to a 3 on 12. Then the gable disappeared. It came back when I changed the pitch back to 8. So it is definitely related to my plan, but not to my roof pitch, because I tried to create a second one on my hip 10 on 12 roof section, and it still did not generate.... Either way, if it does not work on a 3 on 12, I am out of luck, since that's what I want on my porch roof... I guess I will have to learn how to create it manually.