Why don't my prim lighting effects work?

I've been trying to create lights for a photo studio using prims as light sources as i've seen done in several tutorials. When i create a prim and check the light box in the features tab, the prim fails to give off any light even though clicking the radius option shows the perceived radius that the prim should project light. I've got to be doing something wrong of haven't done a proper setting in the tools or advanced tabs. Why don't my prims project light.

Is your photo studio set to 'full bright' textures? If so, they will not react to lighting whatsoever.

i can't get my prims to emit light anywhere. I've tried to get them to do it on the roof of my building, in the public sand box or inside my building. No matter where i render a prim, it does not emit light.

Make sure that "nearby local lights" are enabled in your graphics preferences tab, this is hiding under the custom button in the latest viewers. Also, make sure you aren't inadvertently wearing something with a slew of built-in face lights.

Also due to OpenGL limitations, you can only have 6 lights at a time. The OP of one thread on a similar issue also said disabling "Basic Shaders" in the graphics preferences helped give her the lighting she was seeking.