android scan bluetooth how to do reviciever?

Question

Java

I requested the following rights:

uses-permission android:name="android.permission.BLUETOOTH" />
uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />

On the button, I start the scan and then check:

public void onCreate(Bundle savedInstanceState) {
bt3 = (Button) findViewById(R.id.button3);
bt3.setOnClickListener(btnScanDeviceOnClickListener);
IntentFilter filter = new IntentFilter();
filter.addAction(BluetoothDevice.ACTION_FOUND);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
registerReceiver(bReceiver, filter);

BluetoothAdapter adapter = BluetoothAdapter.getDefaultAdapter();

private Button.OnClickListener btnScanDeviceOnClickListener = new Button.OnClickListener(){
@Override
public void onClick(View arg0) {
adapter.startDiscovery();
tv2.setText("scanning...2");
}
};

private final BroadcastReceiver bReciever = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
tv1.setText("scanning...2");
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
tv1.setText("* "+device.getAddress()+" | "+device.getName()+"\n");
}
else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action) && !adapter.isEnabled()) {
tv1.setText("finish");
}
else if (BluetoothAdapter.ACTION_DISCOVERY_STARTED.equals(action)) {
tv1.setText("start");
}
}
};

I can not understand why it does not find any device.
After starting, "start" immediately pops up, a little later tv1 changes to "scanning2 ...", but nothing else happens.