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:
https://docs.unrealengine.com/latest/INT/Engine/Content/Types/StaticMeshes/LightmapUnwrapping/index.html