[Cin] Speed line

[Sam]

I'm doing an intro for the YT channel and have some problems with the 
speed line.
Is it possible that the speed line can no longer be modified in the 
current version? I have activated it under the menu item "View" "Speed". 
In the video track I see the orange line, but I can click on it as much 
as I want, no new keyframe will be created. Am I doing something wrong 
or was something changed in the meantime? Can anyone confirm this or 
give me some advice?

Sam