Hi again,
Formatdate was not a true date/time value, because of the missing zero at the beginning, I think using Datediff was converting it into date/time for you.
Hopefully the following code is correct:
SELECT *
FROM bk_vAPTData
Where
convert(datetime,formatdate,101) BETWEEN convert(varchar(10),dateadd(D,-1,getdate()),101) AND convert(varchar(10),getdate(),101)