So I have a late 09 i7 iMac hooked to a 24 acd and when I turn the brightness down on the iMac it doesn't effect the 24. How can I make the two monitors brightness be synced. Any help is appreciated. I have tried unplugging the 24 and plugging the usb in as well. Still nothing. I am running the gm of lion as well but I also had this issue in snow leopard.