Iıs 10.0 detailed error 405.0 - method not allowed hatası

                @using (Html.BeginForm("Index", "Vitrin", FormMethod.Post))
                {
                    <form name="sentMessage" id="contactForm" novalidate="novalidate">
                        <div class="control-group">
                            <div class="form-group floating-label-form-group controls mb-0 pb-2">
                                <label>Ad Soyad</label>
                                <input class="form-control" id="name" type="text" name="Ad" placeholder="Adınız ve Soyadınızı giriniz" required="required" data-validation-required-message="Please enter your name.">
                                <p class="help-block text-danger"></p>
                            </div>
                        </div>
                        <div class="control-group">
                            <div class="form-group floating-label-form-group controls mb-0 pb-2">
                                <label>Email Adresi</label>
                                <input class="form-control" id="email" name="Mail" type="email" placeholder="Email Adresinizi Giriniz" required="required" data-validation-required-message="Please enter your email address.">
                                <p class="help-block text-danger"></p>
                            </div>
                        </div>                        
                        <div class="form-group floating-label-form-group controls mb-0 pb-2">
                            <label>Konu</label>
                            <input class="form-control" id="phone" type="text" name="Konu" placeholder="Adınız ve Soyadınızı giriniz" required="required" data-validation-required-message="Please enter your name.">
                            <p class="help-block text-danger"></p>
                        </div>
                        <div class="control-group">
                            <div class="form-group floating-label-form-group controls mb-0 pb-2">
                                <label>Mesajınız</label>
                                <textarea class="form-control" id="message" rows="5" placeholder="Mesajınız" name="Mesaj"  required="required" data-validation-required-message="Please enter a message."></textarea>
                                <p class="help-block text-danger"></p>
                            </div>
                        </div>
                        <br>
                        <div id="success"></div>
                        <div class="form-group">
                            <button type="submit" class="btn btn-primary btn-xl" id="sendMessageButton">Send</button>
                        </div>
                    </form>
                }

    public class VitrinController : Controller
    {
        // GET: Vitrin
        KutuphaneEntities db = new KutuphaneEntities();
        [HttpGet]
        public ActionResult Index()
        {
            Class1 cs = new Class1();
            cs.Deger1 = db.tblKitap.ToList();
            cs.Deger2 = db.tblHakkimizda.ToList();
            return View(cs);
        }
        [HttpPost]
        public ActionResult Index(tblİletisim t)
        {
            db.tblİletisim.Add(t);
            db.SaveChanges();
            return RedirectToAction("Index");
        }