Authentication Forms User Confirmation

I have this code, when I need to enter the User, this line sUserData is set correctly.

  Dim sUserData As String = HttpContext.Current.Request.Cookies("UserID").Value & "|" & HttpContext.Current.Request.Cookies("UserName").Value & "|" & HttpContext.Current.Request.Cookies("UserEmail").Value

  Dim fat As FormsAuthenticationTicket = New FormsAuthenticationTicket(1, _
     HttpContext.Current.Session("UserID"), DateTime.Now, _
     DateTime.Now.AddDays(6), True, sUserData, _
     FormsAuthentication.FormsCookiePath)
  HttpContext.Current.Response.Cookies.Add(New HttpCookie(FormsAuthentication.FormsCookieName, FormsAuthentication.Encrypt(fat)))

Then I have a code where I check if the user is, if he is registered in the Shared (static) method in an open class, like this:

 If HttpContext.Current.User.Identity.IsAuthenticated Then
 EndIf

And this works fine, but if I put the same line in the Page_load instead of the Shared Method class, it will never go into this If statement

  If HttpContext.Current.User.Identity.IsAuthenticated Then
  EndIf

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