How can I output the content in a variable from dbms_output.put_line

In one part of my PLSQL, I try to watch the output from a variable when I loop each time:

select * into v_r11

    from orders
    where product_line_cd = '719D';

dbms_output.put_line( v_r11);

However, I got error message:
PLS-00306: wrong number or types of arguments in call to 'PUT_LINE'

Please help. Received on Wed Oct 25 2000 - 19:37:21 CDT