Children Objects move weird

I have a GameObject (u1) that becomes the parent of another GameObject (u2) but after u2 is placed as a child under u1 something strange happens: when I tell u1 to go to a location u2 doesn't go with it, how do I make go along with it? it seems to be attached because it's rotation will change, but the actual child gameObject wont travel with the parent. is there a way to make them like, attached or something?

P.S. I have a character and when you move that character all the things attached to it move with it, like clothing, and flashlights. but when I make the flashlight a child of my unit in game it doesn't move with it. whats up with that?

Do both objects have rigidBodies? If so you could try setting the child's rigidBody to isKinematic = true.