How to get Back the session value after I set the cookie secure propety to TRUE?

In my web site, I would like to set the cookie security propety to TRUE in the Global.aspx.vb as below.
'Secure Cookie
Dim Coloop1 As Integer
Dim CoArr1() As String
Dim CoCol As HttpCookieCollection
Dim CoItem As HttpCookie

CoCol = Request.Cookies
CoArr1 = CoCol.AllKeys
For Coloop1 = 0 To CoArr1.GetUpperBound(0)
CoItem = CoCol(CoArr1(Coloop1))
CoItem.Secure = True
Next Coloop1

And in my form1.aspx.vb, I set the session value as below.
Session("testingvalue") = "testingvalue"

But after I set the security propety value to TRUE, I cannot get back the prevoius Session value across the page.
Is there anything incorrect in my coding?