Eyes not moving with the head

i’m learning Blender and i’ve made a simple rig to the model in attachment.
When i go to Pose mode and i rotate the head bone or the backbone, i expect the eyes to rotate together with the head but they don’t , they act like a separate object but i’m sure they belong to the character object.

Please can you check the attachment and tell me why is this? personaggio.blend (548 KB)


The eyes have zero weight. In weight paint mode or in the vertex group panel add them to the backbone.001 veretx group with 100% weighting