why are the turrets dark?

i tried lighting them diferently - no luck


sandcastle.blend (449 KB)

check all the normals some aof them are inside so

1 - select all faces then Ctrl-N to recaclculate all the normals

2 - draw the normal and check if all of then are outside
if you have non manifold faces then you may have to select each faces with inward normals and flip them manually in F9


I remade them