So today I finished my first ever install of an amp. The amp and sub sound really good to me, when I play them from my iPod. I used a line out converter to convert the wiring harness signals into RCA outputs, then ran the RCA outputs to my amp. I get no signal to my amp when I play music. I know it's not the amp or the sub, because like I mentioned, the sub and amp are perfectly fine when using other audio sources. Did I tap the wrong wires? I used this chart to determine what wires (I used front speakers and ground).

Maybe I just have bad connections?