Redirect If Not Logged In

Hi all,
I have a page on my website that I only want registered users to be able to go to. This is my code to redirect them if they are not registered.... It doesn't work. Can you help me find what I'm missing?
<script runat="server">

    Protected Sub form1_Load(ByVal sender As Object, ByVal e As System.EventArgs)

        If (User.Identity.IsAuthenticated = False) Then
        
            Server.Transfer("Login.aspx")
            
        End If
        
    
    End Sub
</script>
...