If some bulbs don’t work, that might be, that they coincidentally get a 0 all the time, that should change if you let the blinking run longer.
Also, maybe your computer can’t render the changes fast enough (try looking at them frame by frame, see if the light up then).
I you need it more subtle (if I understand that correctly), apart from changing the speed, you could also try another 4D Texture and play with the Settings (specifically the “échelle”):
