Strange code Debugging

Hi everyone! I'am just trying to move some children to an other gameObject, but only half was been transfered correctly!? Here my code:

        print("old Child Count " + oldGameObject.transform.childCount);
        int i = 0;
        foreach(Transform child in oldGameObject.transform) {
            print("Moving child '" + i + "' to new");
            child.parent = newGameObject.transform;
            i++;
        }

and here the result:

old Child Count 6
Moving child '0' to new
Moving child '1' to new
Moving child '2' to new

And that all... Somebody can explain that?