The antenna itself had duct tape,or the plug on the back of the radio? Either or...if duct tape was on the connector terminal for the antenna plug or the antenna stud outside the vehicle,it may have glue from the tape on it.Clean the glue off with mineral spirits,laquer thinner or acetone.Then reconnect antenna.Glue is an insulator.Not good for things that need bare metal for connecting a circuit.Make sure the antenna mount outside the car is not loose and that thw wire inside the fender is not damaged.