Can't enable cuda 5.5 in old iMac [24 inches, Early 2009] (GeForce 9400M)

Even though my Graphic card is able to support cuda 5.5, it seems not to be working.

When I’m testing it with a GPU sniffer tool, it says:

— GPU Computation Info —
Support not enabled.

Does anyone could help me to get Cuda working on my machine?