Estimote android code detect only one beacon


I have the following code which running fine on Android studio 2.2 and Samsung S5.
Now I use Android 3.5 and Samsung A20.
The same code detect only one beacon.Have you already encounter this issue but the Estimote app detect all of them.
I really need help.

Below is the the code.
private final double MAX_BEACON_DISTANCE = 100;
protected void onCreate(Bundle savedInstanceState) {
beaconManager = new BeaconManager(this);

        beaconManager.connect(new BeaconManager.ServiceReadyCallback() {
            public void onServiceReady() {


		 beaconManager.setRangingListener(new BeaconManager.RangingListener() {
            public void onBeaconsDiscovered(Region region, List<Beacon> list) {
                Integer major = 0;
                Integer minor = 0;
                distanceToClosestBeacon = MAX_BEACON_DISTANCE;
                for (Beacon rangedBeacon : list) {
                    // Estimote  function to compute distance
                    // based on signal's strength
                    Double distanceToThisBeacon = Utils.computeAccuracy(rangedBeacon);
                    if (distanceToThisBeacon <= distanceToClosestBeacon) {
                        distanceToClosestBeacon = distanceToThisBeacon;
                        major = rangedBeacon.getMajor(); // that's how we can get beacon's major ID
                        minor = rangedBeacon.getMinor(); // and that's how we can get it's minor ID
        region = new Region("ranged region", UUID.fromString(stringUUID), null, null);