Discord不会发送特定消息

我目前正在制作Discord机器人 . 我希望它能够访问具有特定查询的API，然后在聊天中显示响应 . 为此，我做了这个命令：

commands.CreateCommand("card").Parameter("user", ParameterType.Unparsed).Do(async (e) =>
    {
        string message = e.Args[0];

        await e.Channel.SendMessage("https://omgvamp-hearthstone-v1.p.mashape.com/cards/" + message + "?collectible=1");

        var r = await Get<RootObject>("https://omgvamp-hearthstone-v1.p.mashape.com/cards/" + message + "?collectible=1");
        Console.Write("Hold it!\n");
        await e.Channel.SendMessage(r.img);
    });

它引用的功能：

public async Task<RootObject> Get<RootObject>(string url)
    {
        using (HttpClient client = new HttpClient())
        {
            client.DefaultRequestHeaders.TryAddWithoutValidation("X-Mashape-Key", "xxxxx");
            client.DefaultRequestHeaders.TryAddWithoutValidation("Accept", "application/json");
            Console.Write("Hang on!\n");
            var json = await client.GetStringAsync(url);
            Console.Write("Not so fast!\n");
            return JsonConvert.DeserializeObject<RootObject>(json);
        }
    }

但是当我发送命令时，它只发回第一个链接以及挂起和不那么快的消息 . 我想要的消息，r.img，只是不发送 . 如何更改代码以便响应我想要的信息？

顺便说一句：

[  
   {  
      "cardId":"EX1_572",
      "dbfId":"1186",
      "name":"Ysera",
      "cardSet":"Classic",
      "type":"Minion",
      "faction":"Neutral",
      "rarity":"Legendary",
      "cost":9,
      "attack":4,
      "health":12,
      "text":"At the end of your turn, add_a Dream Card to_your hand.",
      "flavor":"Ysera rules the Emerald Dream.  Which is some kind of green-mirror-version of the real world, or something?",
      "artist":"Gabor Szikszai",
      "collectible":true,
      "elite":true,
      "race":"Dragon",
      "playerClass":"Neutral",
      "img":"http://media.services.zam.com/v1/media/byName/hs/cards/enus/EX1_572.png",
      "imgGold":"http://media.services.zam.com/v1/media/byName/hs/cards/enus/animated/EX1_572_premium.gif",
      "locale":"enUS"
   }
]

和RootObject.cs：

namespace DiscordBot
{
    public class RootObject
    {
        public string cardId { get; set; }
        public string dbfId { get; set; }
        public string name { get; set; }
        public string cardSet { get; set; }
        public string type { get; set; }
        public string faction { get; set; }
        public string rarity { get; set; }
        public int cost { get; set; }
        public int attack { get; set; }
        public int health { get; set; }
        public string text { get; set; }
        public string flavor { get; set; }
        public string artist { get; set; }
        public bool collectible { get; set; }
        public bool elite { get; set; }
        public string race { get; set; }
        public string playerClass { get; set; }
        public string img { get; set; }
        public string imgGold { get; set; }
        public string locale { get; set; }
    }
}