Uuaah! One bsp-wall is unlited!!!

[legacy-Salem78]

I was playing around in my soon-releasing-map which is a big spaceship and a sunlight is giving the outside a nice light&shadow.
Suddenly I notice one of the walls is unlit and gives a totally white wall in the dark space!?
How? why? I'm just using a simple texture with no shader on the walls and the walls besides have a normal shadow.

Has this happend to anyone else?

[legacy-Bonehed316]

select the surface, push F5, and make sure "unlit" isnt selected.

[legacy-Salem78]

No, "Unlit" wasn't selected.

But I did a fault localization and deleted stuff by stuff and when I deleted a zone-portal close to that wall, the problem disappeared.