If you are talking about the Cuda accelerated Ray-traced rendering warning the just ignore it. If you are talking about something else we need system and version of AE details right down to the last decimal point as well as a detained description of what you are doing to get the error message.
The ray-traced renderer is the pretty much the only thing native After Effects uses the GPU to render. That's an obsolete feature.
Unless you're using that old tool, there's nothing the GPU accelerates. More info here: GPU (CUDA, OpenGL) features in After Effects CS6 and After Effects CC | After Effects region of interest
If you want 3d in AE, I'd highly recommend a third-party plugin like Element, ShapeShifter, or 3d Invigorator as they render very quickly. However, if you want something more powerful or you just don't want to pay, Cinema 4D Lite comes free with AE! More detail here: details of CINEMA 4D integration with After Effects CC
Yong Yin wrote:
The AE that I'm using is "Version 184.108.40.2067"
As a side note, you should consider an update. You're missing a very important bug-fix update to AE! You should be on 220.127.116.11