Changing one po line item but getting error for other line item

Hi,

i am trying to close PO line items by passing delivery completion as 'X' and GR_TO_DATE as system date using BAPI BAPI_PO_CHANGE and i am passing values to POITEM and POITEMX structures.

and i am passing line item 00001, but i am getting errors of other line items 'Delivery of item 00007 of document 30374852 already completed'

Please suggest me on this issue.

Thanks

Narendra