the antenna on the vehicross should be un-powered but im not positive about that.

the 'blue' wire coming out an aftermarket radio is used for powered antenna's (our's may be powered even though it doesnt move)

rowhard- the 'car side' of the blue wire would not be hot because its an input. and it expects 12v when the stereo is turned to the radio function.
honestly, i would hook up the blue wire out of your radio into the 'car side' of the blue and see if it helps your reception.
pretty much you can look at the other side of the connector and see if there is a wire going into the car or not. if there is a wire going out of the stereo connector into the car then its necessary for the 'ant. turn on' to be hooked up.