Can't work with chroma key

[vbl2007]

Maybe I'm repeating myself, but many times I can't work with chromakey files. There are rain / snow / sun ray chroma key footage on both green and blue and alpha-channel backgrounds. I am trying to work with a chroma key in PTE. It turns out very badly: either rain / snow is not visible, or the main picture is very dark under the file with chroma key, there is no transparency. I would like to solve this problem in the new version.