Android :: Send Json String To .NET REST Service From Java?

i am trying to send a json string from my android client to my .net Rest service...

HttpClient client = new DefaultHttpClient();
HttpPost post = new HttpPost("http://myURL");

JSONObject json = new JSONObject();
json.put("name", "i am sample");
StringEntity str = new StringEntity(json.toString());
str.setContentType("application/json; charset=utf-8");
str.setContentEncoding(new BasicHeader(HTTP.CONTENT_TYPE,"application/json; charset=utf-8"));
post.setEntity(str);
HttpResponse response = client.execute(post);

Response is bad request. am i sending the json object as string? is this code correct?