Its probably your module. I've had to replace my module once now the new one is stuffed as well. Originally the module was stuck on down so when i press the button to make the aerial go up, it comes straight back down. Now it wont go down except when i turn the radio off. What you can do is override the module and then the antenna goes up when u turn the radio on, and down when u turn the radio off. The module is located behind the kick panel, but its up quite high near the glovebox.