OEM NAV Rear Camera question

[phileaglesfan]

I have a 2009 Denali XL with OEM NAV/Rear camera. On page 2-61 of the owner's manual it says the NAV screen should display symbols over items in the way when the Ultrasonic system detects them. When I push menu it just allows me to turn the rear camera on and off. Ultrasonic parking assist is on because I can hear it beeping and see the lights flashing.

I know on the 2010 Acadia I drove a yellow triangle would show around the object.

Thanks in advance.