Automated Date for every 2 weeks

Hello There

I have picked up some Oracle SQL which was originally built within a Business Objects query, where the user specified their own dates

I now wnat to take the SQL and run it off a scheduler where no-one has to interact with it

What I am trying to achieve is show data for the last 2 rolling weeks. It is important that there is a also a time stamp so the data picks up the rolling 2 weeks worth of data with the start date always being Midnight and the end date always being 13:00

I have attached an example which presently returns the following error message:

Error: ORA-01830: date format picture ends before converting entire input string
(State:S1000, Native Code: 726)

Code:

I require help with the Between Function

SELECT
ENCOUNTER_WARDSTAY.WARD_STAY_START_DATE
FROM CFIS_DATA.ENCOUNTER_WARDSTAY,
( SELECT level-1 AS day, 12.00 as time
FROM dual
CONNECT BY level <= 400
union
SELECT level-1 AS day, 00.00 as time
FROM dual
CONNECT BY level <= 400) CENSUS_POINTS
WHERE
(to_date(TO_CHAR(ENCOUNTER_WARDSTAY.ward_stay_STAR T_DATE + CENSUS_POINTS.DAY,'DD-MON-YYYY') || ' ' || REPLACE(TO_CHAR(CENSUS_POINTS.TIME,'00.00'),'.',': '),'DD-MON-YYYY HH24:MI')
BETWEEN '16-JUL-2013 00:00:00' AND '31-JUL-2013 13:00:00'

Any help or advice would be greatly appreciated

Thanks
Helen