我想写一个简单的应用程序，发送位到蓝牙设备。现在我不知道什么是错的，我不知道我从哪里得到的错误。我有所有的权限，我要求他们（只有本地化显示在屏幕上）

<uses-permission android:name="android.permission.BLUETOOTH" />
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

我用的是Plugin.BLE NuGet packageStateChangedEvent工作得很好。但是，当我扫描时，没有找到任何设备（即使我有可用于发现的设备）。

public partial class MainPage : ContentPage
    {
        IBluetoothLE ble;
        IAdapter adapter;
        ...
    }
    public MainPage()
        {
            InitializeComponent();
            ble = CrossBluetoothLE.Current;
            adapter = CrossBluetoothLE.Current.Adapter;
            Devices = new ObservableCollection<Device_bluetooth>();
            ble.StateChanged += (s, e) =>
            {
                labelTest.Text=($"The bluetooth state changed to {e.NewState}");
                DisplayAlert("Notice", e.NewState.ToString(), "OK !");
            };
        }

用于扫描以发现以下设备的功能：

// Issue is here
        private async void ScanAsync()
        {
            try
            {
                Devices.Clear();
                adapter.DeviceDiscovered += (s, a) =>
                {
                    Devices.Add(new Device_bluetooth() { Device = a.Device, Name = "Name: " + a.Device.Name.ToString(), Uuid = "UUID:" + a.Device.Id.ToString() });
                };
                if (!ble.Adapter.IsScanning)
                {
                    await adapter.StartScanningForDevicesAsync();
                }
            }
            catch (Exception ex)
            {
                await DisplayAlert("Notice", ex.Message.ToString(), "Error !");
            }

Device_bluetooth是存储设备的类，我在ListView中显示它们，如下所示：

<ListView x:Name="mylistview" ItemsSource="{Binding Devices}" HasUnevenRows="True">
            <ListView.ItemTemplate>
                <DataTemplate>
                    <ViewCell Height="100">
                        <StackLayout>
                            <Frame  BackgroundColor="White"
                              HasShadow="true">
                                <StackLayout HeightRequest="100">
                                    <Label Text="{Binding Name ,Mode=TwoWay}"   />
                                    <Label Text="{Binding Uuid ,Mode=TwoWay}"   />
                                </StackLayout>
                            </Frame>
                        </StackLayout>
                    </ViewCell>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>

请帮帮我我几乎什么都试过了，但我无法科普。