HTTP Post Request: target server failed to response

Hey, I want to build a simple android app for loving the recent track. I receive the song with user.getRecentTrack and send the data and session key to my method but there is an error: "The target server failed to response." Sometimes, there is also Error 3 from the lastfm method: track.love: "Invalid Method - No method with that name in this package". This is my Http Post Request for track.love

HttpClient client = new DefaultHttpClient(); 
String postURL = "http://ws.audioscrobbler.com/2.0/";;
HttpPost post = new HttpPost(postURL); 
List<NameValuePair> params = new ArrayList<NameValuePair>(2);
String signatur = makeTrackLoveSignatur(artist, title, key);
params.add(new BasicNameValuePair("method", "track.love"));
params.add(new BasicNameValuePair("track", tit开发者_如何学JAVAle));
params.add(new BasicNameValuePair("artist", artist));
params.add(new BasicNameValuePair("api_key", api_key));
params.add(new BasicNameValuePair("api_sig", signatur));
params.add(new BasicNameValuePair("sk", key));
params.add(new BasicNameValuePair("format", "json"));

UrlEncodedFormEntity ent = 
new UrlEncodedFormEntity(params,HTTP.UTF_8);
post.setEntity(ent);

HttpResponse responsePOST = client.execute(post); 
InputStream data = responsePOST.getEntity().getContent();

I implemented also a convert InputStream to String method:

BufferedReader reader = new BufferedReader(
                new InputStreamReader(stream));
        StringBuilder sb = new StringBuilder();

        String line = null;
        try {
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
            stream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        System.out.println("Output"+sb.toString());
        return sb.toString();

What's the problem? Thanks...

---

Try adding the Content-type header:

post.addHeader("Content-type", "application/x-www-form-urlencoded");

Here's a similar question in python.