you didn't hook up the trigger wire from the oem harness to your new head unit.
this wire turns on the antenna when you turn on the radio.
i think there should be 2 wires that are left from the original harness.
one will be illumination, and the antenna wire.
turn on the lights and then use a circuit tester to test which one the lights are and then the other should be the antenna wire.

hope it helps.