That error message can be ignored (there is even an option to tell it to never show again).
It means what it says. It is telling you that your GPU is not supported for the acceleration of the ray-traced renderer. This is not a problem because that is an obsolete effect. Now that After Effects comes with Cinema 4D, you have a faster, better, higher-quality way of producing 3d in AE.
As Szalam says, this message refers to an obsolete feature. You can ignore it.
Details of how After Effects uses the GPU are here: http://blogs.adobe.com/aftereffects/2012/05/gpu-cuda-opengl-features-in-after-effects-cs6. html
Thanks for the help!