How do I connect my ipod touch 32GB to my BMW?

I just bought a 2008 bmw 3 series. I tried to connect my ipod through the usb cable and an aux cable that I bought at best buy but it does not work. The idrive shows that the usb device is not supported. What do I do?How do I connect my ipod touch 32GB to my BMW?You need to buy BMW's special cable, not just a regular USB and aux. Here's one: http://www.amazon.com/BMW-Ipod-Adapter-C…