Simulation Error with Calculating Energy Loads

When I run energy simulation for monthly cooling and heating loads, I got the following message.

1. The simulation has not run correctly because of this severe error:

** Severe ** DetermineShadowingCombinations: There are 23 surfaces which are casting surfaces and are non-convex.

What does this mean? 

I have attached the building image in this post. Also input screen as well. I have assigned shading device to HBContext where as others to HBSurfaces.

it is a long corridor facing West, so I have installed lots of louvres along the facade to avoid excessive heating load throughout the year.

I can also upload the file if it is necessary.

Best

John