Lightbaking: my far maps are created,but my near maps won't bake. Why?

I don't quite understand the function of having Dual/Single/Directional Lightmaps. Nothing I've seen explains it, but I thought having dual lightmaps enabled meant Beast would make for me a near lightmap and a far lightmap that would fade-between based on my camera's distance to objects. Isn't this how it works? Here, you can see I do indeed have "Dual Lighmaps" enabled for the last render, and you can see that my near lightmaps are still black somehow.

I can't seem to make my near lightmaps generate, and all I get are the low-res far-lightmaps on my terrain. Any idea what's going on here?