Why I am unable to block login of a user externally in IIS 7.5?

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C#2.0

C#

ASP.NET

web.config

Why I am unable to block login of a user externally in IIS 7.5? i am getting the intranet urls and requesting urls from web.config. Both are made same

in web.config

when hosted. In IIS 6 it works but not in IIS 7.5.

string intranetUrl_101 = ConfigurationManager.AppSettings["INTRANETURL_101"].ToString().ToLower();
                        string intranetUrl_102 = ConfigurationManager.AppSettings["INTRANETURL_102"].ToString().ToLower();

                        string strRequestingUrl = Request.Url.ToString().ToLower();
                        bool login = true;

                        if (Role == "CA" || Role == "C3V" || Role == "C3M") //Restrict to login C3ADMIN via Internet. C3ADMIN allowed only via intranet.
                        {
                            if ((strRequestingUrl != intranetUrl_101) && (strRequestingUrl != intranetUrl_102))//C3 Admin Accessing through internet
                            {
                                lblInvalid.Text = CommonMessage.ShowMessage("102");
                                lblInvalid.Visible = true;
                               login = true;
                                //login = false;
                            }

                        }