Creating WBS element with the Bapi BAPI_BUS2054_CREATE_MULTI

Hi

I need to create WBS elements programmatically. For this I am using the BAPI BAPI_BUS2054_CREATE_MULTI

The fiield tht I am passing are

  wa_wbs_element-wbs_up            = 'P-02-0002-9-011'.

       wa_wbs_element-wbs_element       = 'P-02-0002-9-012'.

       wa_wbs_element-description       = 'TI'.

       wa_wbs_element-proj_type         = 'Z1'.

       wa_wbs_element-responsible_no    = '12'.

       wa_wbs_element-applicant_no      =  '13'

append wa_wbs_element to it_wb_element.

call function 'BAPI_PS_INITIALIZATION'.

call function 'BAPI_BUS2054_CREATE_MULTI'

  exporting

    i_project_definition       = 'P-02-0002'

  tables

    it_wbs_element             =  it_wb_element

     et_return                 =  it_ret.

•   EXTENSIONIN                =

•   EXTENSIONOUT               =.

call function 'BAPI_PS_PRECOMMIT'

tables

et_return = it_ret.

call function 'BAPI_TRANSACTION_COMMIT'

exporting

wait = 'X'

importing

return = wa_ret.

Here  Just before PS_Precommit  I get a msg In the return Paramater of  BAPI  'BAPI_BUS2054_CREATE_MULTI'

'Individual check for creating The WBS Element 'P-02-0002-9-012'. is required..Any Help.. wht is missing ..

thanks