i don't use one anymore but used to and found it to be totally hit and miss depending on what car i was in. My itrip worked fine in the honda i had but not in the zed at all (import) but then i tried a cheapo one off my son's ipod and that did work! No idea why but just ended up getting an ipod head unit in the end anyway. Try taking your aerial off and see if that makes any difference as the more unclear the frequency the better its supposed to work.