iPhone dected web in asp.net C# problem

Question

Hello

I have a code that will detect if the are a iphone or not.

    private static string ua = HttpContext.Current.Request.UserAgent.ToLower();

    public static bool UserAgentiPhone()
    {
        if (ua.Contains("iphone") || ua.Contains("ipod"))
        {
            return true;
        }

        return false;
    }

I have this in my application_start in global.asax

        if (Mobile.UserAgentiPhone() == true)
        {
            Mobile.RewriteiPhone(Context);
        }

and this in my custom url rewriter

else if (Mobile.Mobile.UserAgentiPhone() == true)
            {
                Mobile.Mobile.RewriteiPhone(context);
                return;
            }

RewriteiPhone: public static void RewriteiPhone(HttpContext context) { context.RewritePath("~/UI/Web/Mobile/iPhone/Default.aspx", false); }

When i build the source and test it, this work fine the first time. but it don't work the second time because it's jump or something so the aren't a iphone just only a normaly web.

I can't fine anything when i debbug because the source is being rebuild then any it will work...