The nav light mode changes along with the rest of the instrument panel lighting. Are you seeing the instruments changing from white to orange in low ambient light? The headlight switch has to be "on" or in "auto". The dash lighting mode is separate from the headlights themselves, meaning, if your lights are on in the day, but ambient light is sufficient, the dash lights (and nav) will remain in daylight mode.
Bimmerfest Supporting Member
2011 535i AT | Black Sapphire/Cinnamon | Premium | Heated Sts | Nav | Sirius | Anthracite Hdr & Trim
Prior: 2008 335i 6MT Sedan | Black Sapphire/Terra Leather | Premium | Cold | CA | OEM Alarm
Prior: 2005 330i 6MT | Black Sapphire/Sand Leather | Premium | Cold | UGO | OEM Alarm