K2400B Brightdot Dimming Function

Has anyone managed to get the auto-dimming function to work correctly with the Brightdot clock? Neither of my clocks work properly on this front. I set the off-time to 21 and the on-time to 7 with no brightness (these are both in my kids bedrooms, so they should be off at night) and neither clock turns off…and yes, I do turn the auto-dimming switch to on and save the settings…any ideas?