Xamarin | Android | COSU错误

我正在尝试创建COSU设备。这将是由我公司出售的硬件，该硬件运行由我们开发的单个应用程序。我浏览了许多教程，试图为此建立概念证明。

我目前有以下。

在我的AndroidManaifest.xml中

后来...

<application android:allowBackup="true" android:label="@string/app_name" android:keepScreenOn="true" >
    <receiver   android:name="DeviceAdmin"
                android:label="@string/sample_device_admin"
                android:description="@string/sample_device_admin_description"
                android:permission="android.permission.BIND_DEVICE_ADMIN">
        <intent-filter>
            <action android:name="android.app.action.DEVICE_ADMIN_ENABLED" />
        </intent-filter>
        <device-admin>
            <uses-policies>
                <limit-password />
                <watch-login />
                <reset-password />
                <force-lock />
                <wipe-data />
            </uses-policies>
        </device-admin>
    </receiver>
    <uses-permission android:name="android.permission.MANAGE_DEVICE_ADMINS" />
    <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>
</application>

在device_admin_receiver.xml中

<?xml version="1.0" encoding="utf-8"?>
<device-admin xmlns:android="http://schemas.android.com/apk/res/android">
    <uses-policies>
        <limit-password />
        <watch-login />
        <reset-password />
        <force-lock />
        <wipe-data />
    </uses-policies>
</device-admin>

DeviceAdmin.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using Android.App;
using Android.App.Admin;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;

namespace CB.App
{
    public class DeviceAdmin : DeviceAdminReceiver
    {

    }
}

最后是MainActivity.cs的OnCreate

protected override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);
        Window.DecorView.SystemUiVisibility = (StatusBarVisibility)flags;

        // Setup the collection and register implementations
        IServiceCollection coll = new ServiceCollection();
        RegisterDependencies(coll);

        // Build the global services
        ServiceRegistrationHelper.RegisterCoreServices(coll);

        // Register the provide with the GlobalServices
        GlobalServices.RegisterServiceProvider(coll.BuildServiceProvider(new ServiceProviderOptions()));

        // Set our view from the "main" layout resource
        SetContentView(Resource.Layout.Main);

        DevicePolicyManager myDevicePolicyManager = (DevicePolicyManager)this.GetSystemService(Activity.DevicePolicyService);
        // get this app package name
        ComponentName mDPM = new ComponentName(this, typeof(DeviceAdmin).Name);

        if( myDevicePolicyManager.IsDeviceOwnerApp(this.PackageName))
        {
            //myDevicePolicyManager.ClearDeviceOwnerApp(this.PackageName);

            String[] packages = { this.PackageName };
            myDevicePolicyManager.SetLockTaskPackages(mDPM, packages);
            StartLockTask();
            SetUpClock();
            DisplayHome();
        }
        else
        {
            Toast.MakeText(this.ApplicationContext, "Not Owner", ToastLength.Long).Show();
        }
    }

在ADB Shell中，我运行了命令dpm set-device-owner com.companyname.productname / .DeviceAdmin并收到成功：设备所有者已设置为package componentinfo {com.companyname.productname / com.companyname.productname.DeviceAdmin}主动管理集到组件{com.companyname.productname / com.companyname.productename.DeviceAdmin}

它可以构建和部署，但是当它到达生产线时

myDevicePolicyManager.SetLockTaskPackages(mDPM, packages);

它引发错误Java.Lang.SecurityException：没有活动的管理员ComponentInfo（com.lathem.cumberland / DeviceAdmin

我想念什么？