How can I create a ranking using Google Play Service?

i have a leaderboard. I want to rank for those who play the game.but when I press the ranking button, I only see my score.I dont see the scores of other users logging in and playing the game.

I have one function for that.I want to rank online.
here are my codes;

 private static final int RC_LEADERBOARD_UI = 9004;
      public void siralama(View view) {
               //for online ranking
        try {
        Games.getLeaderboardsClient(this, GoogleSignIn.getLastSignedInAccount(this))
                .getLeaderboardIntent(getString(R.string.leaderboard_skor_tablosu))
                .addOnSuccessListener(new OnSuccessListener<Intent>() {
                    @Override
                    public void onSuccess(Intent intent) {
                        startActivityForResult(intent, RC_LEADERBOARD_UI);
                    }
                });
        }catch (Exception e){
    Toast.makeText(getBaseContext(), "Google hesabınızla oturum açmanız gerekmektedir." , 
    Toast.LENGTH_SHORT ).show();}
    }