I just bought six OmniTik UPA 5HnD units. I am unable to get any of them to power up. I am plugging the power supply into the power connector on the PoE injector and running a CAT5 ethernet cable from the injector to port 1 of the OmniTik. Plugging in the power supply illuminates the PS LED, indicating that the PS is getting AC power. I have tried this with each of the six units and used different injectors/power supplies (that came with the six units). Does anyone have any idea what I'm doing wrong (or what could be wrong)? Please help. I need to get this project going pretty quickly. Thank you.

make sure that the injector end with "DATA+POWER" goes to the OmniTik. what kind of PSU do you use at the injector? How many volts/ampers ?

Also check your Cat5 cable. Make sure all 4 pairs are terminated correctly.

Some fly leads are manufactured with only two pairs connected and this will cause PoE (or Gigabit Ethernet) not to work.