BROBLEM IN BETWEEN QUERY (plpgsql)

hai all,

I have a plpgsql function and I am using postgresl 8.1.9

CREATE OR REPLACE FUNCTION get_vehicle_id(INT) RETURNS SETOF RECORD AS
$BODY$
DECLARE

r RECORD;
int_day ALIAS FOR $1;

BEGIN

FOR r in SELECT fk_bint_old_vehicle_number AS vehicle_id
FROM tbl_rac_vehicle_replacement
WHERE dat_replacement BETWEEN now() - interval '% day',int_day
AND now() LOOP

RETURN NEXT r;
END LOOP;

RETURN;
END
$BODY$ LANGUAGE 'plpgsql';

But i cant craete the function The error message is:

ERROR: syntax error at or near "," at character 137
QUERY: SELECT fk_bint_old_vehicle_number AS vehicle_id FROM
tbl_rac_vehicle_replacement WHERE dat_replacement BETWEEN now() - interval
'% day', $1 AND now()
CONTEXT: SQL statement in PL/PgSQL function "test" near line 11
LINE 1: ...E dat_replacement BETWEEN now() - interval '% day', $1 AND ...

The problem line is BETWEEN now() - interval '% day', $1 AND now()

I want to select dat_replacement between now () and now - 5 dyas or now
-7 days like that i want to pass the integer value as argument to the
function.

I also tried like this WHERE dat_replacement BETWEEN now() - interval
int_day day
AND now(),but it also failed.

Please help me .

regards:
Anoop