Third Brake Light on 2005 GMC Yukon

Regular brake lights work fine. Third brake light does not work. Is this a bulb replacement issue or a fuse issue?

Asked by for the 2005 GMC Yukon
More than likely the bulbs is the third brake light is bad
1 more answer
I have the same issue with mine. Assembly is multiple LEDs so appears to be not getting power. need to take some time to put a meter on to confirm.