Sound system "soft buttons"
 

Hey guys.
I have a standard sound system in my X6, there are 8 called "programable or soft" buttons located below the radio, I was wondering why button #5 is disabled ?
I used the first 4 buttons for my iPod interface ( to browse by artits, playlist, genre or album .......) but when I try to program button #5 is doesnt allow me???
Any hints ? button 6,7,8 are programmed without any trouble

My car does not have NAV system and does not ave CD Changer

Thanks in advance

i programed mine to the phone contacts all 8 work so maybe the button is broken