Volley error PHP Android Studio, not recognizing the POST

Question

I’m having problems with the connector or Android. I really don’t know. I already use Volley in other activities but had never given this problem. Can anyone help me in this? Returns who did not recognize the elements within the POST, as if had not gotten there what came out of Android.

loads the list of players coming from the bank, and chooses one of them, and loads the chosen element of the spinner from the list of actions (e.g., wrong pass), and the URL used, declared in the global:

String url_monta_graf_jogador = "http://192.168.15.17/pizza_acoes_jogador.php";

loadSpinnerJogadores(url_busca_jogadores);
    spinnerJogadores.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
            if (parent.getItemAtPosition(position).equals("Escolha o jogador:")) {
                //faz nada
            } else {
                jogador = spinnerJogadores.getItemAtPosition(spinnerJogadores.getSelectedItemPosition()).toString();
                escolherJogador(acao, jogador);
            }
        }
        @Override
        public void onNothingSelected(AdapterView<?> parent) {

        }
    });

the method that sends both data to the database, and where the problem occurs:

public void escolherJogador(final String nomeAcao, final String nomeJogador){
    Toast.makeText(Graficos.this, nomeAcao+" "+nomeJogador, Toast.LENGTH_SHORT).show();
    RequestQueue queue = Volley.newRequestQueue(Graficos.this);
    StringRequest stringRequest = new StringRequest(Request.Method.POST, url_monta_graf_jogador, new Response.Listener<String>() {
        @Override
        public void onResponse(String resposta) {
        }
    },new Response.ErrorListener(){
        @Override
        public void onErrorResponse (VolleyError error){
            Toast.makeText(Graficos.this, "Erro no servidor", Toast.LENGTH_SHORT).show();
            error.printStackTrace();
        }
    }){
        @Override
        protected Map<String, String> getParams () {
            Map<String, String> params = new HashMap<String, String>();
            params.put("acao", nomeAcao);
            params.put("jogador", nomeJogador);
            return params;
        }
    };
    queue.add(stringRequest);
}

in PHP: the file is called pizza_acoes_gamer.php because the return will be a graph

 <?php 
  require_once("conexao.php");

  $nomeAcao = $_POST['acao'];
  $nomeJogador = $_POST['jogador'];
...
?>

The famous "Notice: Undefined index: action/player in error..."

I would even do it by button, so there’s a strange button there, but it will be owing the same parameters, no use pushing the problem.