Cul-de-Sac give a NIL error.

The biggest thing that people tend to assume incorrectly is that you can draw a Cul-de-sac just anywhere you want in a drawing as long as you have a line to base the center on. This is not the case.

You actually require a street to be defined using the street routines. The centerline of this street will then be used to reference the center of the Cul-de-sac. The other thing is to make sure that the numbers you have entered to design the size of the cul-de-sac will actually work with the street you have.