New switch has power to it but light won't work with switch on I have power at light and with switch off there is power aLos at light. It is a new light

Describe what you have done. Describe the wires in the ceiling and the wires in the switch box. Sounds like you do not have a neutral properly connected How are you determining you have power to switch and to light.

In other words start at the beginning and tell us exactly what you have done.

If the switch is OFF and you have power at the light, you have a wire setup as a switch loop. With power at the switch, you may have another hot for something else.