A/C adapter loose connection. Plug the A/C adaptor securely to the wall outlet and have the D/C plug fully inserted into the 6V DC socket of the unit. Press POWER ON/OFF button. * Wall outlet power switch in off position. If you are plugging your unit into a wall outlet that is operated with a switch, insure the switch is turned on. * Power supply failure. There may have been a power outage or you may have an electrical problem. Try plugging your unit into another outlet - if that doesn't work contact an electrician. * Batteries may not be correctly inserted. Insert the batteries again and make sure that they are placed in the correct direction and polarity as marked in the compartment. * Batteries are empty. Use fresh batteries.