Do you maybe mean this:

WARNING W090: Region leaking
The sky box is not completely closed, or an object is outside, or a large object - like a terrain - is penetrating the sky box, or there is no sky box at all. This is normally not a problem, but can increase the compiling time. However the outer surfaces of the sky box should have the NONE rendering mode set in such a case to prevent a frame rate decrease due to scanning invisible surfaces.

You can search the manual for error messages.

Regards
TSGames