3 scenes into a add and alpha over Im making a animation for some 3D words and i have 3 scenes 1 is the words 2 is a smoke particles and then 3 is like extra particles for color affect. When i go to composting and add them only 3d words show in the pre-render window or the smoke and extra affects appear in the pre-render window. Im watching this guy on YouTube doing and i did the same but his works and my doesn't. My question is why is the alpha over not working with my 3 scenes with a mix set to add with the particles linked?

Extra things if you really want to help
https://www.dropbox.com/s/4xp2cfq0n4jbzaw/Intro%20v3.blend?dl=0
I have found the answer to my question my render for the 3D words was not a transparent in shading.