I own a 2007 chevy cobalt, and i went out and got a new head unit and the wiring kit from best buy. the guy said that chey GM made a blocker on raidos so if you try to put a stolen radio in your car it wont work. so i have to buy a 80$ wiring kit made just for that. I got home and wired it right. the head unit turns on and works but you cant hear any thing out of the speakers. WHAT WENT WRONG..... please help? thank you