Which of your groups/components is not identified as "Solid"? You can check by looking at Entity Info and selecting them one at a time. I would guess it is the sphere that is causing you the problem. Making it the way you did results in an internal face which will prevent the group/component from being regarded as "Solid". Either delete the face of the circle that you are using as the path or draw one circle above the other so they are not intersecting each other.