c# - asp.netのWebHttpRequestメソッド

Question

私のC＃クラス

public class City
{
    public int City_id { get; set; }  
    public string City_name { get; set; }
}

public class Model
{
    public City[] lstCitiesResult { get; set; }
} 

Webリクエスト

string url = "my url";          
WebRequest request = WebRequest.Create(url);

// provide your ID And Password for proxy
request.Proxy.Credentials = new NetworkCredential(XXXX);

WebResponse ws = request.GetResponse();

DataContractJsonSerializer jsonSerializer =
               new DataContractJsonSerializer(typeof(List<Model>));

List<Model> dataList =
 (List<Model>)jsonSerializer.ReadObject(ws.GetResponseStream());

string result = "";

foreach (var data1 in dataList)
{
    result = result + data1.lstCitiesResult.ToString();
}

TextBox1.Text = result.ToString();

私のエラー：データリストでnullになりました...どうすればよいですか？