Bluetooth audio doesn't connect automatically
 

I have a 2013 GL450. I paired my iPhone 4S the day I picked the car up at the dealership and since then the car immediately recognizes the phone as soon as I turn on the ignition. I can make calls using the voice commands or manually without a problem without plugging in the cable.

My issue is that if I want to listen to music from the phone, Comand says that "bluetooth audio is not available" and I then have to manually connect the Bluetooth audio feature each time using the Comand screen. Shouldn't the audio automatically connect when I get in the car the way the telephone does?