help with my radio
 

I have a 02 intrigue and I took out the factory radio and there were 3 plugs one was the antenna one was the main wire harness however I do not know what to do with the third plug it has two wires on it one is black with a white strip and the other is green with a white strip. I hook up all of the wires using a scosche harness after making sure everything was tight i hooked up the battery and nothing. So i took my tester and checked that i am getting 12v to the end of the harness to the radio i am. so after checking everything i unhooked the radio stuck it to the battery and it came on so i hooked it back up and still nothing. i checked to see if im getting juice to the harness and there is. Can anyone please help me out here. thank you