字符串属性未反序列化

我不明白为什么只有字符串属性搜索。值在我的ASP中没有被反序列化。NET MVC5控制器。请参阅:

客户端发送的json结构:

{
   "draw":1,
   // ...
   "start":0,
   "length":50,
   "search":{
      "value":"This is always null in my controller",
      "regex":false
   }
}

我的模型服务器端:

public class AsyncDataTableRequest
{
    public int Draw { get; set; }
    public int Start { get; set; }
    public int Length { get; set; }
    public Search Search { get; set; }
    public string Value { get; set; }
}
public class Search
{
    public string Value { get; set; }
    public bool Regex { get; set; }
}

我想用搜索做一些事情的控制器。价值:

public JToken AsyncLogFetching(AsyncDataTableRequest req)
{
    // req.Search.Value is null here, all other properties seem correct
    ...
}

谢谢你的帮助!

编辑:

对于"NewYork"的示例搜索，这是来自IE开发人员工具中的"request header"选项卡的请求:

GET /Log/AsyncLogFetching?draw=3&start=0&length=50&search%5Bvalue%5D=NewYork&search%5Bregex%5D=false&_=1438350434912 HTTP/1.1

IE开发人员工具中的"请求文本"选项卡显示"没有数据要显示"。

这是执行GET-Request的代码片段，它是copy &从jQuery数据表流水线示例中粘贴:

settings.jqXHR = $.ajax({
    "type":     conf.method, // GET
    "url":      conf.url,
    "data":     request,
    "dataType": "json",
    "contentType": "application/json",
    "cache":    false,
    "success": function (json) {
        // ...
    }
});