Transparency

[Rongyel]

When I use saber of Video copilot, I always create a black solid and click on screen to remove the background, but when I put this composition where the saber is in, in another composition the background is black and not transparent... What can I do to make the background transparent again?

[Rick Gerard]

It would be very helpful if you would spend some time on the Video Copilot site looking at the tutorials and user guide for Saber. Under the render settings is a Composit Options dropdown. All it takes is one click. 

[Rongyel]

I know, that I have to put blending mode screen on it to remove the black
background, but when I port a composition where a saber with blending mode
screen is in, in another comp the background is black and not transparent

[Rick Gerard]

I showed you how to get transparency on a layer with Saber applied. It looks like you didn't try my suggestion. If you have to pre-compose then this is the easiest option by far. If you want to continue to use blend modes when a layer has been pre-composed then you must be using the Classic 3D workspace and you must collapse transformations. 

For any more help, we need to see screenshots of your comp with the modified properties of the layers revealed. Make sure you select those layers and press "uu" before you send the screenshots. We need both comps and a screenshot of the flow chart would also help.