Am I Misusing the LB Radiation analysis tool?

Hi Everyone.

I am trying to use the Ladybug Radiation Analysis tool in to visualize the shading patterns created by a series of parametric shading devices.

However when i input the surfaces i want to analyse the shading on the output is always the same uniform values. I have tried imputing various context geometries, Analysis periods and grid sizes and also rebuilt and flipped the direction of the surface being referenced into grasshopper; always with the same result, shown below. 

I Don't think there is a problem with my definition as when i plug the shading devices themselves into the geometry input the definition works fine.

Am i trying to make this tool do something it isn't designed for, or have i made some other mistake?  Below is my definition, any help would be greatly appreiated. 

-Geoff