Aux cable straight into Audi Concert?

Hi, all I want to do is add an aux input to my standard single din 2004 concert radio. (sounds so simple)

I have seen many people talking about wiring it through the CD changer, but I don't have a changer.

In my car, where a telephone box was connected, there is a wire from 2 pins leading to a 3.5mm jack, which I believe must have outputted sound.
See below..



Using the aux as it is, does not seem to play any sound when I plug my phone/ipod in. I also tried putting the radio into CDC (cd changer mode)

Here is the diagram..



Does anyone know if using this 2 pin aux cable will work and where it should be connected?

Maybe I should try it in the cd changer conector, but I can't locate that from the diagram.

Please help!!

Thanks

Thanks for your advice.

I already had a Sony head unit, so I went ahead and installed this instead, which cost me £30 for adapters!!

So now I have Aux connection but there is no radio reception! Do you know which aerial adapter I need?