Hi,
I am trying to install aftermarket stereo in my audi a3 2006. i purchased the adapter PC9-404 from ebay, initially there was no power in the stereo so i connected the yellow wire to the red one now the power comes to the stereo. however the rear speakers are not turning on. I also connected the blue wire of the with the red connector to the red wire (power), but still now sound from the speaker.
can someone please tell in detail what i need to do, can i make this connector work or is it totally wrong?

I think i have non-bose system, also i do not know if the amplifiers are working or not, a bit new to these things.
i attach here the pics of cables from car, cables from stereo and adapter (head) unit. There are 6 pins in my black iso connector of audi, while there are plugs in the red iso connector plug of the head unit. I do not know what the 2 extra pins are for.

Thanks in advance.