User.Identity.Name Not Working on Production Server

I'm using
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load Message.Text = "Authenticated: " & User.Identity.IsAuthenticated & "<br/>" Message.Text &= "User Name: " & User.Identity.Name End Sub to capture the users windows login.  This works when I am testing the site in the Visual Studio dev server but when I publish that out to the production server I get "False" and no user id.  Any idea why this would work on localhost but not on the actual server? 
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