how to transfer actual cost one wbs element to other wbs element
I have created project and created level 1 wbs element then i book the actual cost for level 1 wbs element.
Then same project i have created level 2 wbs elements, i want to transfer the actual cost from level one to level 2 wbs elements.
Example : level 1 SS-0000001
level 2 SS-0000001-M
here i have booked the actual cost (PO/FI) wbs element is SS-0000001, then i want to transfer wbs element level SS-0000001 to level 2 SS-0000001-M.
i am trying to post through in tcode KB15N but it's asking enter cost element.
please suggest on this process.