Android Lock Screen With DevicePolicyManager

Question

Hi Team good morning now i am working on android device locking.

I need to lock my device(android 2.3.3) using the device keys Volume_up and Volume_down. In this if the volume_up key is pressed the device should lock, if i press volume_down the device should unlock. here is my method.

private void lockNow() {

    if ((dpm.getActiveAdmins() != null) && (dpm.isAdminActive(secureLock))) {
        Intent intent = new Intent(DevicePolicyManager.ACTION_ADD_DEVICE_ADMIN);
        intent.putExtra(DevicePolicyManager.EXTRA_DEVICE_ADMIN, secureLock);
        intent.putExtra(DevicePolicyManager.EXTRA_ADD_EXPLANATION, "is locked");
        dpm.lockNow();
        dpm.setMaximumTimeToLock(secureLock, 0);
        intent.putExtra("force-locked", DeviceAdminInfo.USES_POLICY_FORCE_LOCK);

        startActivityForResult(intent, Extra_Activity);
    } else {
        Log.d("The Device", "Could not lock because device admin not enabled");
    }
}

This lockNow() method used in volume onKeyUp

Manifest:

<receiver
    android:description="@string/admin_app_description"
    android:label="@string/admin_app"
    android:name="app_class_name$MyAdmin"
    android:permission="android.permission.BIND_DEVICE_ADMIN" >
    <meta-data
        android:name="android.app.device_admin"
        android:resource="@xml/admin_app_resource" />

    <intent-filter >
        <action android:name="android.app.action.DEVICE_ADMIN_ENABLED" />
    </intent-filter>
</receiver>

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

The present the device is not locking and no errors. Can any one help me out of this? Note: It will not work with keygaurdmanager and powermanager.