Order By Date ASC - Datatype Is Datetime

I have below SQL, which should be order by posteddate ASC

SELECT AnnouncementID,[Subject],[Description],
CONVERT(nvarchar(10),PostedDate,101) AS PostedDate,
CONVERT(nvarchar(10),ExpiredDate,101) AS ExpiredDate,
CountryID,CreatedBy, CreatedDate, ModifiedBy, ModifiedDate
FROM Announcements a
WHERE isActive = 1
AND CountryID = 2
AND (GETDATE()>= PostedDate)
AND (GETDATE()<= ExpiredDate)
ORDER BY PostedDate ASC

But result is displaying as below, PostedDate datatype is datetime

01/01/2015
01/02/2015
12/28/2014
12/31/2014

Expected result is

01/02/2015
01/01/2015
12/31/2014
12/28/2014