DateDiff giving me the wrong answer

The function for getting the difference in days between two days is giving me a wrong answer here...What could i be doing wrong???

    DateDiff(DateInterval开发者_Python百科.Day, CDate("28/1/2011"), CDate("31/1/2011"))

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For me, it returns 3.

Which is the correct answer according to the documentation on DateDiff.

What were you expecting??