Problem with Function Module

Hello gurus

This is my report code as-

REPORT Z_KK_PO.
TABLES: EKKO,EKPO.

    TYPES: BEGIN OF t_EKKO,
           EBELN TYPE EKKO-EBELN,
        END OF t_EKKO.

    TYPES:  BEGIN OF t_EKPO,
            EBELN TYPE EKPO-EBELN,
            LOEKZ TYPE EKPO-LOEKZ,
            STATU TYPE EKPO-STATU,
            AEDAT TYPE EKPO-AEDAT,
            TXZ01 TYPE EKPO-TXZ01,
            MATNR TYPE EKPO-MATNR,
            EMATN TYPE EKPO-EMATN,
            BUKRS TYPE EKPO-BUKRS,
            WERKS TYPE EKPO-WERKS,
            LGORT TYPE EKPO-LGORT,
            BEDNR TYPE EKPO-BEDNR,
        END OF t_EKPO.

   DATA:  it_EKKO TYPE STANDARD TABLE OF t_EKKO,
          wa_EKKO TYPE t_EKKO.

   DATA:  it_EKPO TYPE STANDARD TABLE OF t_EKPO,
          wa_EKPO TYPE t_ekpo.

**DATA: it_mara1 type ZKK_STR,
**      WA_MArA1 type ZKK_STR1.


SELECT-OPTIONS: S_EBELN FOR EKKO-EBELN.


  INITIALIZATION.
*   S_MATNR-LOW = ' ' .
*   S_MATNR-HIGH = ' '.
*   APPEND S_EBELN.


START-OF-SELECTION.
CALL FUNCTION 'Z_KK_MODULE'
   TABLES
     IT_EKPO       = it_ekpo
     S_EBELN       = s_ebeln
           .


*SELECT EBELN FROM EKKO INTO TABLE it_EKKO
*      WHERE EBELN IN S_EBELN.
*
*  LOOP AT it_EKKO INTO wa_EKKO.
*    SELECT EBELN LOEKZ STATU AEDAT TXZ01 MATNR EMATN BUKRS WERKS LGORT BEDNR
*          FROM EKPO INTO TABLE it_EKPO
*          FOR ALL ENTRIES IN it_EKKO
*            WHERE EBELN = it_EKKO-EBELN.
*



   IF SY-SUBRC = 0.


         WRITE: /10  'LOEKZ',
                 30  'STATU',
                 40  'AEDAT',
                 60  'TXZ01',
                 70  'MATNR',
                 80  'EMATN',
                 90  'BUKRS',
                 100 'WERKS',
                 120 'LGORT',
                 130 'BEDNR'.


   LOOP AT it_EKPO INTO wa_EKPO.



         WRITE: /10  wa_EKPO-LOEKZ,
                 30  wa_EKPO-STATU,
                 40  wa_EKPO-AEDAT,
                 60  wa_EKPO-TXZ01,
                 70  wa_EKPO-MATNR,
                 80  wa_EKPO-EMATN,
                 90  wa_EKPO-BUKRS,
                 100 wa_EKPO-WERKS,
                 120 wa_EKPO-LGORT,
                 130 wa_EKPO-BEDNR.
        ENDLOOP.
      ENDIF.

while using FM , it is not displaying the output and throwing a dump.

Help.

Thanks

Regards

karan