iPhone Bluetooth - unknown song/artist

My dealer setup the bluetooth connection to my iPhone when I picked up the car and it all worked fine. Streaming music over bluetooth worked fine and the touchscreen showed the artist/song etc.

Days later my wife connected her iPhone to the system (via bluetooth) and she can stream her music over bluetooth also, but the touchscreen doesn't know the artist / song title etc. The music on her iPhone has all the required tags just like mine (I set them both up). Her iPhone is running iOS 4 whereas mine is running the latest version, 5.x

Neither phone has been connected to the USB connection.

Any ideas ?