Bevel on inner edge not working

I have two models.

http://dl.dropboxusercontent.com/u/28629176/gamedev/models/bad.blend
http://dl.dropboxusercontent.com/u/28629176/gamedev/models/good.blend

Both are exported to .obj format from sketchup and then imported into blender.

When I try to bevel the inner edge of this part on the bad model, nothing happens:
http://dl.dropboxusercontent.com/u/28629176/gamedev/models/Screenshot%202013-12-09%2001.27.08.png

But on the good model, when I try to bevel that same inner edge, I get bevels:
http://dl.dropboxusercontent.com/u/28629176/gamedev/models/Screenshot%202013-12-09%2001.27.21.png

Why doesn’t the “bad” model allow me to bevel?

If you hide the top face you will see another face connected to the edges you want to bevel. Delete it