I'm confused, it must be getting it's earth through the aerial as you suspected then.
red and white on live make it go up, which is ok, but then you "swap" them around, but they would still be both live!!
Try making the red permanently LIVE, then touch the white on live and watch the aerial go up, removing this White should make it go down, this(white) is the aerial or amp feed from the stereo, so it is only live with the stereo on.
If this doesn't work try it with White permanently live and switch the red on/off.
tabetha