Audi A3 55 plate sport back 2ltr quattro

[lee220591]

I have a Audi A3 55 plate sport back and there is a lead coming out of the glove box with a usb,aux,and a old I phone charger but when I put my phone on to the aux it dose nothing but my phone still plays music but not out loud so its like it's connecting to something but the radio on the cars stays on and I can find anything that would turn it to the aux