I was working on my metal building sealing screws when I realized that I could not go any farther up or down. I started to slide no matter what i did. Had rubber shoes, knee pads strapped to my knees and a seprate pad to keep from sliding. I had to stop where I was and not move because it started me sliding toward the edge with a 15 foot drop. Looked higher from up there. My wife came to help she could not even move the ladder. I don't think I could have made to without sliding off anyway. I told her to call 911 and tell them I could not move without sliding off my metal roof. I have been up there before without any problems and could even walk around being carefful. Now I was in trouble. The fire dept came out and used a ladder to hook over the ridge that I used to climb down to the ladder and to the ground. I don't mind telling you I was terrified I was going to slide off. I was talking to the fireman and he thought it might be the pollen that has been blowing around. I could not see any on the roof or feel any. I've never experienced anything like this before. Is this true. I'm very leery about going back up without some kind of safety hold. I don't think a rope would help because I would have to carry it over the ridge. I have to do some thinking.