Light Function still appearing in shadows

I created a light function caustic texture, applied it to the a spot light to create the illusion of caustics. My problem is that even in the shadow of the lights, the light function caustics still appear… They are also going through a Character so you can see the caustics in the mouth when the mouth is closed… How can I tell it to stop showing the caustics when the light should be being blocked?

Same problem I have encountered. Did you find a solution?