notifyOnReceive on service itself not works.

`
private void notifyOnReceive(Context context, BluetoothGattCharacteristic rx) 
{
  for (Callback cb : callbacks.keySet()) 
{
            if (cb != null ) 
{
                cb.onReceive(context, rx);
      }
        }
    }
`

Here I can not get string value from rx. rx.getStringValue(0) not works. But same thing works on MainActivity.
