change WBS identification for a project
My question is about WBS identification in a project.
My client want to change the WBS identification of the project. thus i have changed the identification for the head WBS and for project definition. I thought that we can change it for all the structure by Project --> Derive Structure but it's written some error message: "Could not find a superior WBS element for WBS element "
it's normal because i have just changed it.
i 'd like to change it automatically in mass, not element by element. how can I make it. and finally, what is the aim of "derive structure" ?