Camera power problem

[kola]

Hi
I have problems with hikvision cameras. I plugged them worked well and a shot 4 cameras do not light anymore. and carrying they are powered with a PoE switch.
when I power on the 12 volts direct it passes. but with the cable rj45 it does not pass. What can be the problem

 

[Phil]

You'll need to follow a process of elimination to find out where the problem lies.
e.g. bring the cameras back close to the POE switch and check them with a short factory-made network patch lead.