问Ajax请求回发一个新页面，而不是部分加载

EN

@using (Ajax.BeginForm("AddJoke", "Home", new AjaxOptions { HttpMethod = "GET", UpdateTargetId = "MyfriendsJokes" , InsertionMode= InsertionMode.InsertAfter}))
{ 
    <div style="display:block">
        <textarea placeholder="Post New Joke" id="newJoke" name="joke" rows="3" cols="50" style="float:left;position"></textarea>
        <button type="submit" id="postnewjoke" style="float:left"> Post </button>

        @Html.TextBoxFor(model => model.fileContent, new { type = "file", id = "fileuploaded", name = "fileuploaded" })
        <div style="display:inline-block">
            <input type="checkbox" name="geo" id="geo" style="width: 100%; float: left; display: block">
            <input name="longitude" style="display:none"/>
            <input name="latitude" style="display:none" />
            <input name="user" style="display:none" value="@Model.user.Id"/>
            <span>Include Location</span>
        </div>
        <span id="jokeError" style="color:red;font-size:14px;"></span>
    </div>
}


<article id="MyfriendsJokes">
    @Html.Partial("_NewJoke")
</article>

       [HttpPost]
    public PartialViewResult AddJoke(string joke, string user, HomePage page,HttpPostedFileBase fileuploaded, string longitude, string latitude)
    {

        Joke newJ = new Joke();
        newJ.Key = Guid.NewGuid();
        newJ.body = joke;
        newJ.facebookID = user;
        newJ.rank = 0;
        newJ.time = DateTime.Now;
        newJ.longitude = longitude;
        newJ.latitude = latitude;
        db.Jokes.Add(newJ);
        HomePage page1 = new HomePage();
        page1.user = Session["user"] as MyAppUser;
        //db.SaveChanges();
        return PartialView("_NewJoke", page1);
    }

@using Jokes.Models
@using Microsoft.AspNet.Mvc.Facebook.Models
@model HomePage

<div style="display:block">
    @Model.user.Name
</div>