急 求助android蓝牙扫描问题onLeScan()不被调用

开启蓝牙扫描，开启显示成功但是回调接口里面的方法onLeScan不被调用，在这个方法中Log打印不出东西 权限开过了 这是什么原因 折磨一天了
package com.example.mrwuchao.bluetoothtest;

import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothManager;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ListView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

public static final int REQUEST = 100;
private BluetoothAdapter adapter;
private List<String> list = new ArrayList<>();
private ListView listView;
private ListAdapter listAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    listView = (ListView) findViewById(R.id.blue_list_view);
    if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
        Toast.makeText(this, "该设备不支持蓝牙BLE", Toast.LENGTH_SHORT).show();
    } else {
        BluetoothManager manager = (BluetoothManager) getSystemService(BLUETOOTH_SERVICE);
        //获得蓝牙适配器
        adapter = manager.getAdapter();
        if (adapter == null || !adapter.isEnabled()) {
            Intent intent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(intent, REQUEST);
        }

    }
    listAdapter = new ListAdapter(this, list);
    listView.setAdapter(listAdapter);
}
//定义的按钮点击的处理方法
public void scan(View view) {
    Log.i("scan", "点击了扫描");
    final BluetoothAdapter.LeScanCallback mLeScanCallback =
            new BluetoothAdapter.LeScanCallback() {
                @Override
                public void onLeScan(final BluetoothDevice device, int rssi,
                                     byte[] scanRecord) {
                   Log.i("scan","终于回调了");
                }
            };
    if (adapter.isEnabled()) {
        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                adapter.stopLeScan(mLeScanCallback);
                Toast.makeText(MainActivity.this, "扫描结束", Toast.LENGTH_SHORT).show();
            }
        }, 15000);
        boolean b = adapter.startLeScan(mLeScanCallback);
        Log.i("scan", "" + b);
        //10秒后停止扫描

    } else {
        Toast.makeText(MainActivity.this, "蓝牙不可用", Toast.LENGTH_SHORT).show();
    }
}

}

http://www.cnblogs.com/savagemorgan/p/3722657.html

你用的手机是android系统6.0的吗？哪个需要动态权限