Why your new light fixtures dont come on when you have 120V at the socket?

My first suspicion is you have a loose or disconnected neutral. TURN THE BREAKER OFF WHEN CHECKING THE CONNECTION. To include all points, even the obvious, make sure you have changed the lamps to known working lamps from another fixture. How do you know it has 120 volts at the socket? If you tested it with a voltage tester or a multimeter, which wires were you connected to? In order to troubleshoot you need to make three measurements, at the BOXif wall or ceiling mounted or RECEPTACLE if plugged in with a cord, not the fixture socket the lamp screws into. Hot to ground (volts AC) Should be 120 volts nominal. This can vary from about 110-130v. Hot to neutral (volts AC) Should be 120 volts nominal. Neutral to Ground (volts AC) Should be 0 volts. These wires are electrically joined at your main panel. If you have 120v hot to neutral, your circuit is working properly. Any problem will lie in the fixture or the connections to the fixture. If you do not have 120v to neutral but you do have 120v hot to ground, your neutral is not connected. TURN THE BREAKER OFF and check the connection. If you do not have 120v to neutral or120v to ground, your hot is not connected. TURN THE BREAKER OFF and check the connection. If you have anything other than 0 volts neutral to ground, your fixture connection may be okay, but your neutral is not connected properly going back to the main panel. This is a dangerous situation, and it can result in fire over time. In this case have an electrician inspect the situation immediately!