Why "layered blend per bone only works with parent bone" only works from parent bone?

Hi,

I try to blend a body idle animation with a eyes-blinking animation

it only works if I set the bone name to “DEF-head”

if I set ‘DEF-eyeLids’ , then it does not work anymore

any reason why it works that way ?

I now have to create an additional bone that does not do anything but be there as a “placeholder” for the blending

image

I just dont get it, I only want to blend DEF-eyeLids, not DEF-head

ok nevermind, it started working for some reason