解析JSON对象数组:“最好的重载方法match有一些无效参数”

我使用JSON.net来解析我从PHP脚本中获得的对象数据。

我可以让它解析数组并将其分解。然后当我试图解析数组中的每个对象时我得到了这个错误:

Additional information: The best overloaded method match for 
'Newtonsoft.Json.JsonConvert.DeserializeObject(string)' 
has some invalid arguments

这是给我错误的函数:

    public void updateSearches()
    {
        var bw = new BackgroundWorker();
        bw.DoWork += (send, args) =>
        {
            WebClient client = new WebClient();
            JSON = client.DownloadString("URL");
            dynObj = JsonConvert.DeserializeObject(JSON);
            foreach (var item in dynObj)
            {
                dynamic search = JsonConvert.DeserializeObject(item);
                foreach (var s in search)
                {
                    joined += string.Join(",", s) + "END OF THE LINE'r'n";
                }
            }
        };
        bw.RunWorkerCompleted += (send, args) =>
        {
            this.mainWindow.richTextBox2.Text += "Got Data!'r'n";
            this.mainWindow.richTextBox2.Text += joined;
        };
        bw.RunWorkerAsync();
    }

我昨晚刚开始学习c#，所以我是一个新手。如果您需要更多的信息，请告诉我。