hmm... doesn't look like you're doing anything wrong. it's just that i don't think the chromakey effect will work at the same time as the basic 3d effect.
i know, i'm sorta stressing the point a lot, but Axogon is the way to go. it has something called a blending mode that will take out all the black values of the stock footage realistically. If you can't get it installed, you just click on the download thing and open the .exe file to run the installer.
i'll make a step-by-step tutorial on how to do it. it's really not all that hard
"Animation is about creating the illusion of life. And you can't create it if you don't have one." - Brad Bird