430 How to play music from CF card

I am trying to use the CF slot in the Becker head unit on an 08 F430 to play mp3 files. I have one folder loaded on the CF card which is FAT32. After inserting the card, I cannot figure out how to get it to read. Radio, obviously plays the radio and if I select Media it looks for an external AUX source. The manual seems to say it will automatically start playing but that doesn’t happen. Ideas?
Thx, Mike