'01 Denali Cd Changer install

Hello
I am trying to install a factory 6-CD changer into an 01 Denali XL. The connector is in place and i hooked it up (8pin) but when i press on the radio "CD/TAPE" button it does not switch to the CD

Do i need to have the BCM reprogrammed by the dealership or what? Also does anyone have a description of the 8pins on the back of the cd changer - that way i can check that its receiving 12volts

thanks