Only half my maps lightmap will work.

I created a small level that just goes around in a loop, and later, decided I wanted to expand it. but now, when I try to bake the new lightmap for the whole level, it only bakes the new portion that I added, and the rest of the level goes without lights. I have the whole level in one... folder I guess you could call it? I tried baking that whole thing, it didn't work, and I tried baking all the lights, and that didn't work either.