my mesh turns black when using static light

Somehow my meshes turn black when using static lighting. I read somewhere about setting the “index resolution corrdinates” (or whatever its name is) to 512, but that’s not solving the issue for me.

I attach pics of how the mesh should look like, and how it’s actually rendered. In the pictures i use a spotlight, but using point light causes the same issue (haven’t tried the other light types).

any ideas? :confused: