For a sec... I thought Rawburt was back...
First... did you ahrdwrie the radio in, or use the harness?
You have a power antenna, I assume? When you installed the HU, did you hook the power antenna lead to the wrong wire? The (I belive) blue wire that comes from the dash should be hooked up to the HU's "power antenna wire" for the "remote turn on". If this isn't hooked up,the antenna will not work.
The hu tells the antenna to go up, not the car. BEcuase remeber, when you turned the power off of you factory HU, the antenna went down. Your new HU has to do the same, that is what the blue wire from the HU wire harenss is for. WHen the power is on for your HU, the antenna will go up.
The wire in the new HU's harness should say right on it "Power antenna " or "remote turn on". Must be hooked up to either one of these.