DBMS_OUTPUT where ?

I'm new at PL/SQL.
Why doesn't the following produce any output ? I'm logged is as SYS.

Thanks, BOB.

Connected to:
Oracle7 Server Release 7.2.2.3.0 - Production Release PL/SQL Release 2.2.2.3.0 - Production

SQL> begin
  2 dbms_output.enable;
  3 dbms_output.put_line ('test');
  4 end;
  5 /

PL/SQL procedure successfully completed.

SQL> (ok - so where's the output ?)   Received on Mon Mar 25 1996 - 00:00:00 CET