Unable to assign data to dataSource in kendoComboBox

[Cosmin]

I have a big problem populating a kendo combobox with json data sent from controller in an ASP.NET MVC3 project.
My controller:

public JsonResult Index()

{

  StreamReader sr = null;

  string json = string.Empty;

 

  WebRequest request = WebRequest.Create("http://192.168.1.8:99/GetClienti?format=json");

 

  using (WebResponse response = request.GetResponse())

  {

    sr = new StreamReader(response.GetResponseStream(), true);

    json = sr.ReadToEnd();

  }

 

   int index = json.IndexOf('[');

   json = json.Substring(index);

   index = json.LastIndexOf(']');

   json = json.Substring(0, json.Length + 1 - Math.Abs(index - json.Length));

 

 

  return Json(json, JsonRequestBehavior.AllowGet);

}

I am modifying the returned string to be an array of objects (dataSource works only for arrays from what I have read)

In the html file:

...

<input id="kendoCboClienti" />

...

<script type="text/javascript">

    $(document).ready(function () {

    $("#kendoCboClienti").kendoComboBox({

            placeholder: "Sceglie il cliente",

            dataTextField: "RAGIONE_SOCIALE",

            dataValueField: "ID",

            dataSource: {

                transport: {

                    read: {

                        url: "/Clienti/",

                        dataType: "json"

                    }

                },

                schema: {

                    model: {

                        fields: {

                            id: { type: "number" },

                            ragioneSociale: { type: "string" }

                        }

                    }

                }

            }

        });

    });

</script>

In the attachment below is the json the controller returns. The combobox control doesn't show anything, just the loading image in the right.

It's a problem with the Json? If I declare it locally, it works (in firebug appears like an object array of objects). The dataSource can't parse it? It's because of the json is like a string, in the " ? I don't know what the problem might be, I spent too many time trying to understand this..

Please help! Thanks!