datename (wd....)

[Microsoft]

I am getting incosistent / incorrect daynames from my data using the
datename function. I get the correct dayname and months for dates in
September but, incorrect daynames and correct months for dates in august
july etc..

the query i am using is:

SELECT
DATENAME(WEEKDAY,DAY(SaleDate)) AS Dayname,
DATENAME(MONTH(SaleDate)) AS MonthName,
SaleDate
FROM Sales

the results are:

Dayname Month Saledate
----------------------------------------------------------
Saturday August 2003-08-27 00:00:00.000 -
Incorrect (should by Wednesday)
Tuesday September 2003-09-02 00:00:00.000 - Correct


any help would be greatly appreciated

Ozz