If the dash switch is disconnected, the lights won't go down. Could be unplugged, a break in a wire, the switch itself, et al.
Some times you'll hear and feel a click when you plug that button in, but it can still magically work itself loose. If you just had the radio bezel out for some reason, chances are it's just not fully connected. If you haven't touched anything there recently, and this just started happening, you might very well need to replace the switch.
I've also heard that there's a flasher under the dash panel under the steering column, by the door buzzer, that will cause the same thing. I've personally never found that to be the cause, but that doesn't mean it can't happen.