Field Symbol in Control Break Statement

If we use field symbol rather than normal work area then the value of the table remains unchanged. It means it doesn't convert into *** and zero into the corresponding fields.

TABLES ekpo.
FIELD-SYMBOLS: <it_ekpo> TYPE STANDARD TABLE.

INITIALIZATION.
  SELECT-OPTIONS s_ebeln FOR ekpo-ebeln.

CLASS pur DEFINITION.
  PUBLIC SECTION.
    TYPES: BEGIN OF ts_ekpo,
             ebeln TYPE ekpo-ebeln,
             ebelp TYPE ekpo-ebelp,
             txz01 TYPE ekpo-txz01,
             ktmng TYPE ekpo-ktmng,
             meins TYPE ekpo-meins,
             netpr TYPE ekpo-netpr,
             peinh TYPE ekpo-peinh,
           END OF ts_ekpo.
    DATA dref TYPE REF TO data.
    METHODS: ekpo, output.
ENDCLASS.

CLASS pur IMPLEMENTATION.
  METHOD ekpo.
    CREATE DATA dref TYPE TABLE OF ts_ekpo.
    ASSIGN dref->* TO <it_ekpo>.

    SELECT ebeln ebelp txz01
           ktmng meins netpr peinh
      FROM ekpo INTO TABLE <it_ekpo>
      WHERE ebeln IN s_ebeln.
  ENDMETHOD.

  METHOD output.
    FIELD-SYMBOLS: <wa_ekpo>  TYPE ts_ekpo,
                   <flag>     TYPE char1,
                   <subtot>   TYPE any,
                   <subprice> TYPE any,
                   <grandtot> TYPE any,
                   <grandpr>  TYPE any.

    IF <it_ekpo> IS ASSIGNED.
      CREATE DATA dref TYPE p DECIMALS 2.
      ASSIGN dref->* TO <subtot>.
      CREATE DATA dref TYPE p DECIMALS 2.
      ASSIGN dref->* TO <grandtot>.
      CREATE DATA dref TYPE p DECIMALS 2.
      ASSIGN dref->* TO <subprice>.
      CREATE DATA dref TYPE p DECIMALS 2.
      ASSIGN dref->* TO <grandpr>.
      CREATE DATA dref TYPE char1.
      ASSIGN dref->* TO <flag>.

      LOOP AT <it_ekpo> ASSIGNING <wa_ekpo>.

        AT NEW ('EBELN').
          <flag> = 'X'.
        ENDAT.

        IF <flag> = 'X'.
          WRITE: / <wa_ekpo>-ebeln,
               12  <wa_ekpo>-ebelp,
               20  <wa_ekpo>-txz01,
               45  <wa_ekpo>-ktmng,
               60  <wa_ekpo>-meins,
               65  <wa_ekpo>-netpr,
               80  <wa_ekpo>-peinh.

        ELSE.
          WRITE: /12 <wa_ekpo>-ebelp,
                 20  <wa_ekpo>-txz01,
                 45  <wa_ekpo>-ktmng,
                 60  <wa_ekpo>-meins,
                 65  <wa_ekpo>-netpr,
                 80  <wa_ekpo>-peinh.
        ENDIF.

        <subtot>   = <subtot>   + <wa_ekpo>-ktmng.
        <grandtot> = <grandtot> + <wa_ekpo>-ktmng.
        <subprice> = <subprice> + <wa_ekpo>-netpr.
        <grandpr>  = <grandpr>  + <wa_ekpo>-netpr.

        AT END OF ('EBELN').
          WRITE: / '==================================================',
                 / 'Subtotal',
                 50 <subtot>,
                 70 <subprice>.
          CLEAR: <subtot>, <subprice>.
        ENDAT.

        AT LAST.
          ULINE.
          WRITE: / 'Grand Total',
                 50 <grandtot>,
                 70 <grandpr>.
        ENDAT.

        CLEAR <flag>.
      ENDLOOP.
    ENDIF.
  ENDMETHOD.
ENDCLASS.

START-OF-SELECTION.
  DATA po TYPE REF TO pur.
  CREATE OBJECT po.
  CALL METHOD: po->ekpo,
               po->output.