Rendering issue

I have this weird effect

It should be yellow but it gets dark.
Does sb know how to fix this issue?

It’s best to provide more information. Where are you lighting the scene from (a light inside the room or outside?), does the model have a 2nd UV channel properly unwrapped for the lightmap? If you do have the lightmaps setup properly, is the resolution set high enough?

More on lightmaps:

Thx there were some problems with lighting .
Scene was inside and I did use BSP to make it