If you have the AudioText option then you have the correct radio and the CD Changer is sending the ID3 data to the radio (the radio then relays it to the Nav computer which displays it on the screen). If the radio does not send the ID3 info messages then the AudioText option is not there.

There is only one possibility I can think of, your Nav software is not late enough to support the new text screen. The text display mode was added in V24, although no one knew what it was at the time. Which Nav software version do you have (Settings menu top right, it should be 4-1/40 or higher)?