update in triggers

Hi,

Think im doing something wrong here, cant seem to resolve the problem i
have a trigger which is calling a update function and when it gets to a
update it goes into a infinite loop

code

Trigger
CREATE TRIGGER "new_trigger" AFTER INSERT OR UPDATE
ON "chargeratetest" FOR EACH ROW
EXECUTE PROCEDURE "chargeratetest"();

function

CREATE OR REPLACE FUNCTION "chargeratetest" () RETURNS trigger AS'
begin

UPDATE chargeratetest
set notes=''hello''
where new."primary" = chargeratetest."primary";

return null;
end;
'LANGUAGE 'plpgsql' IMMUTABLE CALLED ON NULL INPUT SECURITY INVOKER;

would be greatful for any help thx