I have a query to fetch date diff between 2 datetime as :
SELECT DATEDIFF(DAY, @CreatedDate , GETDATE()) Ex : SELECT DATEDIFF(DAY, \'2013-03-13 00:00:00.00
Try this, may this will help you
SELECT DATEDIFF(DAY, DATEADD(DAY,-1,'2013-03-13 00:00:00.000') , GETDATE())