Not able to update field MARA-IPRKZ through BAPI

Hi,

I am trying to upload data from Excel file to Material Master through BAPI BAPI_MATERIAL_SAVEDATA , able to upload data in Material Master . But i am getting issue in one filed , MARA-IPRKZ.

* When i pass any data in this field MARA-IPRKZ bapi_mara1-period_ind_expiration_date = is_data-iprkz.

bapi_marax-period_ind_expiration_date = 'X'.

I am getting error as " The value W is not allowed for the field ". If i try to do force upload through SQL update after material creation through BAPI , system allows to update the data , but when i check in MM02 , in Plant Data / Stor. 1 TAB , i am getting warning message "Customizing table of period indicators is incomplete ".

Can anyone suggest to fix this issue , urgent pl.

BR,

Murali