Possibly age. I just looked up "A1136" and that seems to be a 5th gen iPod (the "iPod video"). It's old, but that model was often the cut-off for support (for being supported). The only way to find out what your car's audio system officially supports is to find the specificaltions.
If the car audio system has a mini-stereo jack as an aux. audio input, you can connect your iPod from the headphones jack to the aux. input using something like this
For an older iPod, that may be a better way to connect it, because it is simple. There is no interaction between car system and iPod taking place. The iPod just needs to play music like always, except it is playing through the car system instead of through your headphones.