Return data between two dates in the past

Hello - does anyone know why the statement "where WD.WRKD_WORK_DATE BETWEEN DATEADD(DD, -6, GETDATE()) AND GETDATE()) = 0' is successful, but "WD.WRKD_WORK_DATE BETWEEN (DATEADD(DD, -16, GETDATE())) AND (DATEADD(DD, -3, GETDATE()))" is an invalid statement? I've tried a lot of different syntax variations of this statement and cannot get to work between two lookback dates. Thanks for any clues!