rule calls function, passing OLD

Hello.
I am a beginner with pgsql and struggeling with the documentation.

Why can't I pass OLD from my rule to the function so the function knows
on which row the rule was called?

test=# \i '/home/myAccount/Documents/Datenbank Layout/Postgres
Sytax/test/Regeln2'
CREATE FUNCTION
psql:/home/myAccount/Documents/Datenbank Layout/Postgres
Sytax/test/Regeln2:16: ERROR: function
deny_namen_telefonverweise(namen_telefonverweise) does not exist
HINT: No function matches the given name and argument types. You may
need to add explicit type casts.
test=#

When I pass an integer instead, everything works.

Is there another way of letting the function know on which row the rule
was called?

CREATE OR REPLACE FUNCTION deny_namen_telefonverweise(record) RETURNS
void AS '
DECLARE
result RECORD;

BEGIN
/* DELETE ROW LATER */
SELECT 1+1;

END;
'
LANGUAGE 'plpgsql';

CREATE OR REPLACE RULE deny_namen_Telefonverweise AS ON DELETE TO
Namen_Telefonverweise
DO INSTEAD
SELECT DENY_Namen_Telefonverweise(OLD);