Why isn‘t my OnCharacteristicChanged triggered?

Question

The problem is "how can my code dont trigger the OnCharacteristicChanged...i set the notification to true ma the only result that i have is this:
Connected to GATT server.
Service : android.bluetooth.BluetoothGattService@bf8aa7
Qui entra, service non nullo
Found characteristic: 00005303-0000-0041-4c50-574953450000
Characteristic supports notifications.
Found characteristic: 00005302-0000-0041-4c50-574953450000
Characteristic does NOT support notifications or indications.
Characteristic for notifications found and notifications set.
Descriptor for notification written successfully.
onDescriptorWrite :Sucess
Disconnected from GATT server, status: 8

this is my code:

public CompletableFuture<Void> connect(String deviceAddress)
    {
        CompletableFuture<Void> future = new CompletableFuture<>();

        BluetoothManager bluetoothManager = getSystemService(BluetoothManager.class);
        BluetoothAdapter bluetoothAdapter = bluetoothManager.getAdapter();
        device = bluetoothAdapter.getRemoteDevice(deviceAddress);

        gatt = device.connectGatt(null, false, new BluetoothGattCallback()
        {
            @Override
            public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState)
            {
                 if (newState == BluetoothGatt.STATE_CONNECTED) {
                    BA.Log("Connected to GATT server.");
                    gatt.discoverServices();
                } else if (newState == BluetoothGatt.STATE_DISCONNECTED) {
                    BA.Log("Disconnected from GATT server, status: " + status);
                    future.complete(null);
                }
            }

            @Override
            public void onServicesDiscovered(BluetoothGatt gatt, int status)
            {
                if (status == BluetoothGatt.GATT_SUCCESS) {
                    BluetoothGattService service = gatt.getService(UUID.fromString(SERVICE_UUID));
                    BA.Log("Service : " + service);
                    //attualmente stampa Service : android.bluetooth.BluetoothGattService@bf8aa7  con 00005303-0000-0041-4c50-574953450000
                    //attualmente stampa Service : android.bluetooth.BluetoothGattService@ad02a43 con 00002902-0000-1000-8000-00805f9b34fb
                    if (service != null)
                    {
                        BA.Log("Qui entra, service non nullo");
                        
                        BluetoothGattCharacteristic characteristic = service.getCharacteristic(UUID.fromString(CHARACTERISTIC_UUID_NOTIFY));
                        if (characteristic != null)
                        {
                            gatt.setCharacteristicNotification(characteristic, true);
                            startReadBlock = true;
                            BA.Log("Characteristic for notifications found and notifications set.");

                            //Before onCharacteristicChanged is called you had to enable notification. Someting like:
                            BluetoothGattDescriptor descriptor = characteristic.getDescriptor(UUID.fromString("00002902-0000-1000-8000-00805f9b34fb"));
                            descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
                            gatt.writeDescriptor(descriptor);
                             BA.Log("Descriptor for notification written successfully.");

                        }else
                        {
                            BA.Log("Notification characteristic not found.");
                        }
                    }
                }
            }

            @Override
            public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic)
            {
                byte[] data = characteristic.getValue();
                BA.Log("Received HandleRX: " + bytesToHex(data));
                if (startReadBlock) 
                {
                    BA.Log("START READDATABLOCK");
                    readDataBlock(data);
                }
            }

            @Override
            public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
                if (status == BluetoothGatt.GATT_SUCCESS) {
                    BA.Log("Characteristic written successfully.");
                } else {
                    BA.Log("Error writing characteristic: " + status);
                }
            }

            @Override
            public void onDescriptorWrite(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status) {
                super.onDescriptorWrite(gatt, descriptor, status);
                BA.Log("onDescriptorWrite :" + ((status == BluetoothGatt.GATT_SUCCESS) ? "Sucess" : "false"));
            }
        });

        return future;
    }

i stay for hour to add log for trying to step with code but nothing....are days that i am in this problem