How to keyframe "Use Count" in particle system? I want to change the distribution of objects in a particle system between two frames.
Though there is an option to keyframe I cannot get it to work.



Am I doing something wrong? Or is there a bug?
I am using Blender v2.76.

Example file:
http://s000.tinyupload.com/index.php?file_id=72573226735559326311
In frame 1 I want to have 20 times as many icosphere as cubes.
In frame 2 I want to have 20 times as many cubes as icosphere.
You have keyframed the checkbox that enables or disables 'Use Count', not the 'Count' values themselves, which are shown below the large yellow box in your screenshot.

However, trying to keyframe the actual 'Count' value displays an error message, which indicates that these values probably can't be animated.

I would suggest posting another question on this site asking specifically about how to get different amounts of particles to appear.