iPhone 4s and honda 2012 usb

So my mom recently bought a used 2012 honda accord and it has a USB plug in. I tried to plug her phone in and it starts charging and displays that the phone is plugged in. When I put a song on it displays the song info, but no audio is passing through (volume is on for the car, but no volume control is present in the music app). Any ideas what the problem may be?

Phone: 4s
OS: 6
Music: Default music app