Update product hierarchy in Material master

Hi Gurus,

I want to update the product hierarchy in basic data view of material mast with some new product hierarchy.

Business requirment: My client is changing the prduct hierarchy values EG : currently it is 010010000100000001

                                                                                                                   new value may be : 020020000200000002.

The lenght of the levels will remain same : 02 03 05 08.

only the value will be changing.

I am serching any BAPI or FM which will update the material  master PRDHA. I tried using 'BAPI_MATERIAL_SAVEDATA'

i am passing the values as

HEADDATA like BAPIMATHEAD

MATERIAL = '000000000000200000'
BASIC_VIEW = 'X'.

CLIENTDATA like BAPI_MARA

PROD_HIER = '020090004600000118 '

CLIENTDATAX like BAPI_MARAX

PROD_HIER = 'X'.

and then caling BAPI_TRANSACTION_COMMIT.

Am i missing something here??

it is not updating the values with 020090004600000118.

when i went to MM02 i found that product hierarchy field is not in edit mode..i m now not understanding how to update the old PRHDA of MARA with new PRHDA value? please help..