Short dump in BAPI_PO_CHANGE

HI all,

I am using BAPI_PO_CHANGE to change the Quantity and Item text of PO items .

The following is the function call :

Loop at loop at z_i_item assigning <z_f_item>.
call function 'BAPI_PO_CHANGE'
      exporting
        purchaseorder                = <z_f_item>-ebeln
     tables
       return                        = z_i_return
       poitem                        = z_i_poitem
       poitemx                       = z_i_poitemx
      poschedule                     = z_i_posch
      poschedulex                    = z_i_poschx
       potextitem                =  z_i_itemtxt .
Endloop.

Am filling all the internal tables in the " tables parameter " for every loop of z_i_item.

But it throws a short dump as soon as the BAPI is executed .

" The current ABAP "SAPLMEPO" program had to be terminated because the

ABAP processor detected an internal system error.

When exporting the structure description, the structure

components overlapped. The error occured in the

description of the object "XEKPO". "