Issues with simple chroma keying in 2.5

Hey, I’m trying to composite a zippatone dot effect into a simple scene as an exercise for my first animation. I’m following this tutorial here to key out a green section of the image and replace it with an image file. The only difference between his example and mine is that instead of keying out a green background, I’m trying to key out a green material, and that I didn’t add a blur or scale node, since I do not need either.

However, my results are nothing like those presented in the video. While the video works exactly as you would expect, my results look like this:

This is my node setup:

If anyone can help me with this, I’d really appreciate it.

I’m not sure what the setup you’re following is supposed to look like, but just going by your node tree; you pull an alpha out with the keyer which is good, but you never actually use it to define the alpha when you composite the other plate on top, you simply slap it on top which would result in the result you’re getting. You’ll need to use the matter output on the ChromaKey to define the alpha for the mix node. I can’t, off the top of my head, remember how to do that right now, but if you play around for a bit you should be able to figure it out.

Oh crap! The YouTube link I inserted didn’t work! I’ll edit the post! XD

After messing around it appears that setting the Fac setting in the Mix node to 1 creates the desired results. Not really sure why, because as you said I never defined the alpha, but, yea, at least its behaving…