Sprite Renderer.Cast Shadows Functionality

I just upgraded to Unity 4.3 and am playing around with the new sprite features. Originally I was using the Transparent-Cutout-Diffuse shader in order to achieve shadows from sprites in a 3D environment. With Unity2D, this functionality is placed into the Animation window, but I'm not sure how to link it all up.

As of right now, I have a scene with a Point Light with Hard Shadows on, and a fireplace sprite using the Sprites-Diffuse shader, and some space purposefully left between the fireplace and the wall. The fireplace has an Animator component, with a Sprite Renderer.Cast Shadows curve. However, no shadows are being cast on the wall or floor behind it. I'm not sure what I need to hook up where in order to get the sprite to cast a shadow. Can anyone help?