using SPUtility.EnsureAuthentication(spWeb) i am redirecting the page but it not happening.

hi,

requirement is to check the credentials of the user at the login page and if true then redirect from that login page to home page.

i am using this following code:

            SPSite spServer = SPControl.GetContextSite(Context);
            SPWeb spWeb = SPControl.GetContextWeb(Context);
            SPUtility.EnsureAuthentication(spWeb);
            SPUtility.Redirect(spWeb.Url, SPRedirectFlags.UseSource, Context);

i am not able to redirect the page.it is not ensuring the user or not evaluating the user credentials(windows credentials).the control is not coming at the sputility.redirect,