1994 Honda Accord dash light won't work

My car's dash board light won't work. All warning lights are functioning. I change the instrument light for illuminating the dash board. But it still won't work, I also notice that every time the headlight was switch on. The Transmission indicator in the dashboard turns off. If the headlight was off the Transmission lndicator light works. I suspect that there is an open ground somewhere. Could you be able to point me in the right faulty components.