What's wrong with my Unreal Editor 4?

i can import a FBX-File (exported directly from Sketchup). Do this mesh into scene (nothing else) and Push “Build” and then the Scene and the mesh looks o.k. The mesh and the Lightning is fantastic.
If it do it a second one (i exported in Sketchup the same mesh with another name). Imported this into UE4 and push “Build” this second mesh is dark not usual.
What is wrong with my UE4? It’s exactly the same FBX-Model.
Please help me, i don’t know what i should do now.

You have to use a second UV-Channel for the lightmaps