Chrona Key dosn´t work!

When i want to use the chroma key simple it doosn´t work and the green background dont go away

sry for my bad english im form Germany

Works fine here.
But you have not given us anywhere enough information about what steps you are taking, which version of Shotcut you are using or even which operating system.
I don’t think anyone here are mind readers :wink:

Basic informations here :

You can try to search if there is a youtube tutorial in German.