Android BroadcastReceiver无法正常工作

Question

我创建了我的启动器，现在我希望在打开屏幕后出现我的锁屏。这是我的清单和BroadcastReceiver代码。

<?xml version="1.0" encoding="utf-8"?>
  <manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="de.mq.empol"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="14"
    android:targetSdkVersion="17" />

<uses-permission android:name="android.permission.VIBRATE" />

<application
    android:allowBackup="true"
    android:debuggable="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >


    <activity
        android:name="de.mq.empol.LockActivity"
        android:label="@string/app_name"
        android:theme="@android:style/Theme.Light.NoTitleBar.Fullscreen" >
        <intent-filter>                  
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity 
        android:name="de.mq.empol.MainActivity"
        android:label="@string/title_activity_main"
        android:theme="@android:style/Theme.Light.NoTitleBar.Fullscreen" 
        android:launchMode="singleInstance"
        android:stateNotNeeded="true">
        <intent-filter> 

            <action android:name="android.intent.action.MAIN" />      
            <category android:name="android.intent.category.HOME"/>
            <category android:name="android.intent.category.DEFAULT" />
        </intent-filter>
    </activity>

    <receiver android:name=".Receiver">
    <intent-filter>
            <action android:name="android.intent.action.ACTION_POWER_CONNECTED" />
    </intent-filter>
    </receiver>

</application>

 </manifest>



package de.mq.empol;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;

public class Receiver extends BroadcastReceiver {

@Override
public void onReceive(Context context, Intent intent) {
    Intent act = new Intent(context, LockActivity.class);
    act.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    context.startActivity(act);  

}

 }

我希望按下电源按钮后启动我的锁屏，但为什么这不起作用？你有解决方案吗？