Man! The all-caps made it feel like I was being yelled at .

I first built the level with no skybox at all to see what would happen. I've done this many times and never have received this error. I then added a skybox and still got this error.

In any case, I wish WED would tell you WHERE the leak was so that you could fix it. Obviously WED knows theres a leak (in order to report it) so it seems that WED would have to know WHERE the leak was (in order to know there was one!).