A wired occlusion culling phenomenon in unity3d, could you help me fix it?

I found a wire occlusion culling problem. Something in my view, but they acre culled. And give a back a black hole. They look like:

• In picture1, There is a floor mesh, but it is gone, when I open the occlusion culling, but when I shutdown it, it showed as normal.

• In picture2, the whole ground is culled, also it is in the view.

Do you know how to fix it? It nearlly made me crazy.

I got the solution to fix this problem.

It is

• Decreasing the value of smallest hole in occlusion culling's baking setting

There is a Chinese post, Unity4.3遮挡剔除：故障排除 talking about this problem.