I don't know if this is helpful cause i've stopped playing simcity.
Many of the bats i had downloaded didn't ligh up until many months had passed in the game.
I don't know why's that...maybe there weren't enough people in the buildings to switch on the lights!
Other than that , have you installed every update Maxis has released?
If yes have you tried reinstalling the specific update fot the illumination of the bats?
can't think of something else