넷위버 7.0 트라이버젼으로 실습하는데 아래의 문제가 생겨 질문을 드립니다.

1. 결과를 확인하니 아래의 메세지가 나옵니다.

method "set(exporting" is unknown or protected or private.

아무리 뒤져봐도 뭐가 잘못됐지 알수가 없네요.

 *&---------------------------------------------------------------------*
*& Report  Z17_003
*&
*&---------------------------------------------------------------------*
*&
*&
*&---------------------------------------------------------------------*

REPORT  z17_003.

*----------------------------------------------------------------------*
*       CLASS counter DEFINITION
*----------------------------------------------------------------------*
*
*----------------------------------------------------------------------*
CLASS counter DEFINITION.
  PUBLIC SECTION.
    METHODS: set IMPORTING set_value TYPE i,
             increment,
             get EXPORTING get_value TYPE i.

    DATA count TYPE i.
ENDCLASS.                    "counter DEFINITION

*----------------------------------------------------------------------*
*       CLASS counter IMPLEMENTATION
*----------------------------------------------------------------------*
*
*----------------------------------------------------------------------*
CLASS counter IMPLEMENTATION.
  METHOD set.
    count = set_value.
  ENDMETHOD.                    "set

  METHOD increment.
    ADD 1 TO count.
  ENDMETHOD.                    "increment

  METHOD get.
    get_value = count.
  ENDMETHOD.                    "get
ENDCLASS.                    "counter IMPLEMENTATION

DATA: cref1 TYPE REF TO counter,
      l_imp TYPE I.

START-OF-SELECTION.

  CREATE OBJECT cref1.

  CALL METHOD cref1->set(exporting set_value = 3).
  WRITE: / 'set method:', cref1->count.

  CALL METHOD cref1->increment.

  CALL METHOD cref1->get(importing get_value = l_imp).
  WRITE: / 'get method:', l_imp.

2. 실행을 하니 아래의 메세지가 나옵니다.

method "set" is not declared or inherited in class "counter"....

e아밥 홈페이지에 있는 소스를 그대로 이용한건데 위 메시지가 나오네요.
뭐가 잘못됐나요?

REPORT  z17_004.

CLASS counter DEFINITION.
    PRIVATE SECTION.
*    PROTECTED SECTION.
    DATA count TYPE i.
ENDCLASS.

CLASS counter2 DEFINITION INHERITING FROM counter.
  PUBLIC SECTION.
    METHODS: set IMPORTING set_value type i,
             increment,
             get EXPORTING get_value type i.
ENDCLASS.

CLASS counter IMPLEMENTATION.
  METHOD set.
    count = set_value.
  ENDMETHOD.
  METHOD increment.
    ADD 1 TO count.
  ENDMETHOD.
  METHOD get.
    get_value = count.
  ENDMETHOD.
ENDCLASS.

DATA : CREF1 TYPE REF TO COUNTER2,
       L_imp   TYPE I.
START-OF-SELECTION.
CREATE OBJECT CREF1.

CALL METHOD CREF1->SET( exporting set_value = 3 ).

CALL METHOD CREF1->increment.

CALL METHOD CREF1->GET( IMPORTING get_value = l_imp ).
WRITE : / 'GET METHOD :' , l_imp.

위 내용에 대해 자세한 조언부탁합니다.

추석 마지막입니다. 잘 보내세요.^^