radar detector not working.helpp!

my brother (:screwy:) put in a new radio..and it didnt work. so now he put my old aftermarket one in and now my radar doesnty work.i checked the fuses and all were fine especially my cig lighter one. the radar works in others peoples cars just not mine.what could be wrongg? i dont want 130$ being put to waste...:frown:


thanks,
emily

did you check the fuses under the hood ?