CAD import file boundary conditions

I have a 2D model I've imported from CAD that consists of many interlinked hexagons making up a larger hexagon (like a big hexagon with smaller hexagon-shaped holes throughout). I'm trying to do a steady-state diffusion simulation in COMSOL using this model, but I'm stymied when it comes to identifying boundary conditions. I go to physics---->boundary settings, but all the boundary selections are grayed out and unavailable. I thought this might be some issue with the interior boundaries, but toggling that option has no effect (all boundaries are still unavailable). I have no problem constructing a system from scratch and entering BC's. Does anyone know what might be wrong? Using COMSOL 3.5a, diffusion module.

I've tried Googling this problem til my eyes bled, but to no avail.