Platform edge showing through exterior wall material

[cbrillante]

I have a 1 1/2 story house (essentially an attic buildout) and have cedar shake shingles defined as my exterior wall material on the 2nd floor. When looking at the front wall of house, a band of white is showing in the front gable above the gable windows. I have set the exterior wall material for the gable wall on the 2nd floor and the attic wall above it to cedar shakes. All other 2nd floor gables display properly except for this one. I have tried using the painter tool with cedar shakes selected as the material, but when I click it on this area, a message is displayed saying that the color cannot be applied to the edge of a platform. I have a vaulted ceiling and this appears to be showing at the same location as my ceiling touches the outside wall, just can't figure out why or what this "platform edge" is. Any ideas?

Thanks a bunch!!!