upload with jqueryform and mvc

I'm trying to upload an image file using ajaxForm(). Somehow the server never gets the request. here's some code:

$('form').ajaxForm({
    iframe: true,
    type: "POST",
    dataType: "json",
    url: '/UploadPictureId',
    data: {
        academicPhotoId: $('#AcademicPhotoId')
    },
    success: function (result) {
        alert("win");
    }
});

and here's the method code:

开发者_StackOverflow社区    [HttpPost]
    public JsonResult UploadPictureId(HttpPostedFileBase AcademicPhotoId)
    {

        return Json(...);
    }

A few things to check:

• See my comment about making sure it's pointing to the correct URL in the first place.
• Your form should have enctype="multipart/form-data" on it.
• You may also have to set the response type to text/html as noted here