Installed a new recessed 6 inch can light fixture and dimmer switch in a room remodel. Wired black to black, white to white, ground to ground. Light does not work. Voltage measurement at the fixture with the switch turn on. Zero volts - black to white; 120 volts black to ground (can). At the Switch I has Black hot on one terminal - Black to light on the other terminal. Whites are nutted together. Light blub is good, switch is good also. What is wrong?

If you have no voltage black to white and 120v black to ground at the light you have an interrupted neutral (white). Check connection of white (neutrals) at the switch.