I was going to try a new bulb but checked the manual and the bulbs are different sizes than the extra brake light one I have. Going to have to wait for a day off so I can get a new bulb and see if that works. And yes, I do know the difference between a back-up light and cargo light, I just misspoke in my original post.
Also I have not relocated any switches so I'm sure it's not because of that. The only thing that I've done to it is remove the entire light housing to smoke it. It was then that I realized that it was out, but to be honest it could of been put before that because I never checked it prior.
I guess my only question that remains is if the bulb is out (Which makes sense because the cargo lights work), would that give me a lamp out indicator?