Ambient light sensor not working?

I have a question about the light sensor. I have a mid-2010 mac book pro with 10.8.5 OS X. I have never seen my display or keyboard change brightness when the light source changes. iStat shows the light changes when I put my hand or thumb over the iSight area. I can see it running around 14 - 28 lx before covering the iSight up and going down to something around 4 lx or so when the area is covered up. The Keyboard and the Display brightness stays the same. Both the Keyboard and Display have a checkmark for using the Auto Brightness. I have tried unchecking and rechecking the boxes and I have restarted them system both as just rebooting and as a cold start. I thought about trying the SMC reset but I am not sure that would do anything since the sensor itself seems to be working according to iStat. Any other suggestions as to why its not working?