Loop through records

Hi all,
I'm a PostgreSQL novice (obviously)...
I' trying to write some test functions to iterate over recordsets...

this is one:

CREATE OR REPLACE FUNCTION "public"."new_allarma" (soglia name) RETURNS
text AS
$body$
DECLARE
    rec RECORD;
    agent text;
BEGIN

     FOR rec in SELECT * from "ERRORS" where "MAX_ERRORS" > = soglia limit 3
    LOOP
        RAISE NOTICE '--> RECORD  --> ';
    END LOOP;
    RAISE NOTICE 'Complete';
    RETURN 'OK';
END;
$body$
LANGUAGE 'plpgsql' VOLATILE CALLED ON NULL INPUT SECURITY INVOKER;

It doesn't even print the string --> RECORD  --> as I supposed it to do...

but raises the error:ERROR:  record "rec" is not assigned yet
DETAIL:  The tuple structure of a not-yet-assigned record is indeterminate.
CONTEXT:  PL/pgSQL function "new_allarma2" line 6 at for over select rows


Now i ask: how can I iterate through a recordset and print something,
suppose the entire record ( or better its fields) ?

Thanks in advance.

Best Regards,

Emil.