关于转换的未知错误

Question

我已经将这个angularJs调用到了asmx WebMethod，但是我收到了有关转换的错误。这里代码为

AngulaJs致电：

$scope.delete = function (idNews) {
    var url = '/data_db.asmx/SetDeleteNews';
    var obj = idNews
    $http.post(url,obj)
    .success(
        function (response) {
            if (response.Error) {
                console.log('Impossibile to remove.' + response.Message);
            }
        })
    .error(
        function (response) {
            console.log('Error:' + response.ExceptionType);
            console.log(response.Message);
            console.log(response.StackTrace);
        });
}

WebMethod，在C＃中：

public bool SetDeleteNews(int i)
{
    News n = new News
    {
        id = i,
        title = string.Empty,
        arg = string.Empty,
        isDeleted = true,
    };

    bool result = BONewsLINQ.DeleteNews(n);
    return result;
}

和BO：

public static bool DeleteNews(News delete)
{
    using (Entity news = new Entity ())
    {
        try
        {
            News remove = news.News.Where(n => n.id == delete.id).FirstOrDefault();
            news.News.Remove(remove);
            news.SaveChanges();
            return true;
        } catch
        {
            return false;
        }
    }
}

错误是：

Error:System.InvalidOperationException
Cannot convert object of type 'System.Int32' to type 'System.Collections.Generic.IDictionary`2[System.String,System.Object]'
at System.Web.Script.Serialization.ObjectConverter.ConvertObjectToTypeInternal(Object o, Type type, JavaScriptSerializer serializer, Boolean throwOnError, Object& convertedObject)


at System.Web.Script.Serialization.ObjectConverter.ConvertObjectToTypeMain(Object o, Type type, JavaScriptSerializer serializer, Boolean throwOnError, Object& convertedObject)
   at System.Web.Script.Serialization.JavaScriptSerializer.Deserialize(JavaScriptSerializer serializer, String input, Type type, Int32 depthLimit)
   at System.Web.Script.Serialization.JavaScriptSerializer.Deserialize[T](String input)
   at System.Web.Script.Services.RestHandler.GetRawParamsFromPostRequest(HttpContext context, JavaScriptSerializer serializer)
   at System.Web.Script.Services.RestHandler.GetRawParams(WebServiceMethodData methodData, HttpContext context)
   at System.Web.Script.Services.RestHandler.ExecuteWebServiceCall(HttpContext context, WebServiceMethodData methodData)

我只传递一个int值（在var obj中），但是返回此错误。为什么？感谢