I have a problem.
Both of the eyes blink without problems but only the puppet's right eye follows my eyes but the left one does not.
When I turn on the mesh feature I can see there is a mesh around the left eye.
Is that the reason why the left eye does not move?
How can I make the left eye follow the right eye?
It is usually a tagging error (a layer has the wrong tag on it). I would go through every layer of the left and right eyes (expand them all) and check the tags are the same (but one is left vs right). A common problem is the L/R Pupil Range layer is not bigger than the eye pupil, so there is no space left for it to move. I notice you have a "white" and "L/R Eyeball" layers - I would check their tags in particular.
What does it mean that their could be wrong tag?
In the "Rigging Issues" there is one diagnosed issue:"Layer tagged as Left Pupil Size is not being used by any behaviors"... Can this be the problem why my left pupil does not move? How can I resolve this?
wrong screenshot, heres the correct one:
quick response - it looks like Left Pupil has a single child Left Pupil and the child is independent. This is different to right Pupil. Try removing the independent flag of the nested layer (same as right pupil) and see if that works.
As soon as I see an independent layer with *all* children (in your case just one) independent, then its usually a bug. Child independent layers need some artwork in the parent layer to "attach" to, so need at least one child to be not-independent.
If that does not work I will go into tagging in more detail, but the above might be the problem.