Not working in ACAD2006 with simple rectangle.
Command: roof
Pick 2d polyline
Pick point inside 2d polyline
Enter choice (2D / 3D) : 2D
Unknown command "ROOF". Press F1 for help.
Requires numeric distance, two points, or option keyword.
Unable to extrude the selected object.
Unknown command "ROOF". Press F1 for help.
1 face found.
Modeling Operation Error:
No solution for a vertex.
Unknown command "ROOF". Press F1 for help.