Session logout problem

<script language="javascript" type="text/javascript">
        var sessionTimeoutWarning = 1;
        var sessionTimeout = '<%= Session.Timeout %>';
        //alert(sessionTimeout);
        var sTimeout = parseInt(sessionTimeoutWarning) * 60 * 1000;
        //        setTimeout('SessionWarning()', sTimeout);
        setTimeout('SessionWarning()', sessionTimeout);
 
        function SessionWarning() {
            var img = new Image(1, 1);
            img.src = '<%= System.Configuration.ConfigurationSettings.AppSettings["SitePath"].ToString()%>/KeepAlive.aspx?date=' + escape(new Date());
//            var message = "Your session will expire in another " +
//	(parseInt(sessionTimeout) - parseInt(sessionTimeoutWarning)) +
//	" mins! Please Save the data before the session expires";
//            alert(message);
        }
</script>