Change Limits of a PO Using BAPI_PO_CHANGE

Hi,

I am trying to change the overall limit and Expected value in the Limits tab using BAPI_PO_CHANGE .

But I am not able to update, I am able to update other item level - Netpr.

<fs_excelitab> - It is the values from the excel, which has ebeln,ebelp,netpr, sumlimit, commitement.

*- PO Header data

    v_purchaseorder     = <fs_excelitab>-col001.

*- PO Item data

    t_poitem-po_item    = <fs_excelitab>-col002.

    t_poitem-net_price  = <fs_excelitab>-col003.

    APPEND t_poitem.

*- PO Item data for Update

    t_poitemx-po_item   = <fs_excelitab>-col002.

    t_poitemx-po_itemx  = 'X'.

    t_poitemx-net_price = 'X'.

    APPEND t_poitemx.

*- PO Limits

    t_polimits-pckg_no   = '0001'.

    t_polimits-limit     =        <fs_excelitab>-col004.

    t_polimits-exp_value = <fs_excelitab>-col005.

    APPEND t_polimits.

*-- Calling BAPI function module

      CALL FUNCTION 'BAPI_PO_CHANGE'

        EXPORTING

          purchaseorder = v_purchaseorder

•          testrun       = p_test

        TABLES

          return        = t_return

          poitem        = t_poitem

          poitemx       = t_poitemx

          polimits      = t_polimits.

      CALL FUNCTION 'BAPI_TRANSACTION_COMMIT'

        EXPORTING

          wait = space.

Thanks in advance