Keyframes for Scaling DON'T WORK

[thomash40238564]

Whenever I try to set keyframes for scaling an image or videofile, it just sticks with the scale of the first keyfram and doesn't change. However, the keyframes for other effects such as position and rotation are completely fine. 
I already tried:
-Restarting program
-Nesting
-Changing the file

Can anyone help me out?

[Ann Bens]

Try transform effect instead.

[thomash40238564]

That does seem to work. Tough I discovered something new. It's not the effect itself that is the problem, but the preview is. Cause it works whenever I put a horizontal flip on the file. Then the animation of the changing size will be previewed with no problem. So I only have this problem when I want to preview it. Cause it also renders fine in the end. But still, this could be a glitch or a bug. 

[Ann Bens]

If you use horizotal flip nest before using motion keyframes.