This is my problem: I have created a Static Mesh throught a BSP (that I use like floor of my kitchen), after that I notice that something was wrong, and I have continued working, then when I do a Build lights, the mesh was rendered in black absolutely. I thought that this was because a bad normal mapping but seeing the mesh all looks great (at least I think so), searching in google I found some Ideas like do two sided materials and other that dont remember now.
Please help me in try to discover where is the problem, thanks and sorry for my english.
The following image is the Static Mesh after lighting builds::
And the next image is in static mesh editor in that you can see the normals and tangents of the mesh.