Guid Null after create user using CreateUserWizard

I followed this security turorial.
http://www.asp.net/learn/security/tutorial-08-vb.aspx


I'm getting Null error in this line

Dim newUserId As Guid = CType(newUser.ProviderUserKey, Guid)


The code works if I'm logged in, but in my case, annoymous users create accounts...
It's not like admin create accounts...


In CreateUserWizard, I have set -   LoginCreatedUser="True"
Does it mean you log in after pressing create account in the first page of CreateUserWizard?
What am I missing???


Thank you for your help



---VB-code behind---

Protected Sub CreateEmp_CreatedUser(ByVal sender As Object, ByVal e As System.EventArgs) Handles CreateEmp.CreatedUser
        Dim checkuser As String = User.Identity.IsAuthenticated

        Dim newUs ...