PLS-00306:过程调用中的参数数量或类型错误

以下SQL导致Oracle 11g错误: PLS-00306: wrong number or types of arguments in call to 'PRINT' 。但在我看来,它就像我的 print 过程需要1个varchar2参数,而这正是我作为参数传递给它的内容。

CREATE TABLE employees (full_name VARCHAR2(64))
//

INSERT INTO employees (full_name) VALUES ('John')
//

INSERT INTO employees (full_name) VALUES ('Paul')
//

INSERT INTO employees (full_name) VALUES ('George')
//

INSERT INTO employees (full_name) VALUES ('Ringo')
//

CREATE OR REPLACE PROCEDURE print (
  v_string IN VARCHAR2
) IS
BEGIN
  dbms_output.put_line(v_string);
END print;
//

DECLARE
  v_string VARCHAR2(64);
BEGIN
    FOR v_string IN (SELECT DISTINCT full_name
                            FROM  employees) LOOP
        print (v_string);
    END LOOP;
END;
//

我可以在SQLFiddle中重现这个问题: http://sqlfiddle.com/#!4/c0e80e/6

我错过了什么?

谢谢