Passing parameters to triggers

I have a severe problem when working with PL/pgSQL triggers. Somehow the
problem seems to be strange. Here is the code:

CREATE OR REPLACE FUNCTION checkint () RETURNS opaque AS
'
        BEGIN
                IF      TG_OP = ''DELETE'' THEN
                        RAISE NOTICE ''% wert'', TG_ARGV[0];
                        DELETE FROM TG_ARGV[0];
                END IF;
                RETURN OLD;
        END;
' LANGUAGE 'plpgsql';

CREATE TRIGGER trig_a_b AFTER DELETE OR UPDATE ON a
        FOR EACH ROW EXECUTE PROCEDURE checkint('b');

DELETE FROM a;

When running the code I get a strange problem. The RAISE NOTICE command
works but somehow the DELETE statements displays an error.

NOTICE:  b wert
NOTICE:  Error occurred while executing PL/pgSQL function checkint
NOTICE:  line 4 at SQL statement
ERROR:  parser: parse error at or near "$1"

Does anybody know what I can do?

    Hans