Unable to update Item Text using Bapi_po_change

Hi Experts,

I am unable to update Item Text Field sing BAPI_PO_CHANGE.

Here is my Code

CLEAR: lt_item[], lt_itemx[], lt_extensionin[].

***Udating standerd fields

str_item-po_item = str_itemx-po_item = ekpo-ebelp.

str_item-stge_loc = ekpo-lgort.

str_itemx-stge_loc = 'X'.

str_item-CONF_CTRL = '0004'.

str_itemx-CONF_CTRL = 'X'.

*** str_item-weightunit = ekpo-gewei.

*** str_itemx-weightunit = 'X'.

*** str_item-volume = ekpo-volum.

*** str_itemx-volume = 'X'.

*** str_item-volumeunit = ekpo-voleh.

*** str_itemx-volumeunit = 'X'.

APPEND str_item TO lt_item.

APPEND str_itemx TO lt_itemx.

*****************below is the issue***************

***Updateing Recharge flag

str_flag-PO_NUMBER = ekpo-ebeln.

str_flag-PO_ITEM = ekpo-ebelp.

str_flag-text_id = 'F99'.

str_flag-TEXT_FORM = ' '.

str_flag-text_line = stxl-tdspras.

APPEND str_flag TO lt_flag.

****************************************************************

***Updating New Z-fields in EKPO*

str_bapi_te_mepoitemx-po_item = ekpo-ebelp.

str_bapi_te_mepoitemx-zzdest_wellsite = 'X'.

str_bapi_te_mepoitemx-zzkostl_tms = 'X'.

str_bapi_te_mepoitem-po_item = ekpo-ebelp.

str_bapi_te_mepoitem-zzdest_wellsite = ekpo-zzdest_wellsite.

str_bapi_te_mepoitem-zzkostl_tms = ekpo-zzkostl_tms .

str_extensionin-structure = 'BAPI_TE_MEPOITEM'.

str_extensionin-valuepart1 = str_bapi_te_mepoitem.

APPEND str_extensionin TO lt_extensionin.

str_extensionin-structure = 'BAPI_TE_MEPOITEMX'.

str_extensionin-valuepart1 = str_bapi_te_mepoitemx.

APPEND str_extensionin TO lt_extensionin.

CALL FUNCTION 'BAPI_PO_CHANGE'

EXPORTING

purchaseorder = ekpo-ebeln

TABLES

return = i_return

poitem = lt_item

poitemx = lt_itemx

extensionin = lt_extensionin

POTEXTITEM = lt_flag.

CALL FUNCTION 'BAPI_TRANSACTION_COMMIT'

EXPORTING

wait = 'X'.

please let me know what is the issue or any alternate way to update it.

Regards,

Aniket Kumar