Hi Leonard, I checked out your file, and yes it does just seem to be not illuminated well...

Note that the edge that you are talking about is angled downward somewhat like this:



So that means that a light shining from directly above it will not illuminate it, it is hidden from that light.

The main one that could possibly illuminate it would be this light over here:



That's light#4, but you seem to have disabled it so that it does not do anything in the renderer currently, note that "Visible in Renderer" for that light is set to Off:



You'll need to enable that light and possibly adjust the overall lighting some more to make that edge not be so dark.


As far as I can tell your model data is all perfect, you just need to shine some light on that area if you don't want it to be dark.

- Michael