Light building problem on eyes

So I brought 2 meshes, where one has 2 eyes, while the other has a head along with the eye meshes as a whole object. When I build lighting, the right eye in the whole mesh has been darkened why is tht?
The normals and uvs are fine, and i also dont get the darkening problem when I import the eyes separately.

If it’s a character then you don’t need to build lighting for it because it will need to animate and won’t use baked lighting.

sorry for the late reply, thanks for the info