System.Reflection.TargetInvocationException将设置页面实例化为MasterDetail菜单中的导航页面

System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation尝试从MasterDetail菜单启动设置页面时出现错误。从研究中我知道，这意味着无法实例化该页面。这是页面的xaml。

我正在使用James Montenegro的xam.plugins.settings存储设置。很卡住了。

    <?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
                         xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
                         x:Class="EIOBoardMobile.Views.SettingsPage"
                         Title="Settings">
    <ContentPage.Content>
        <StackLayout>
            <Label Text="Connection Information" />
            <StackLayout>
                <Grid>
                    <Grid.RowDefinitions>
                        <RowDefinition Height="*" />
                        <RowDefinition Height="*" />
                        <RowDefinition Height="*" />
                        <RowDefinition Height="*" />
                    </Grid.RowDefinitions>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="*" />
                    </Grid.ColumnDefinitions>
                    <StackLayout Orientation="Vertical" Grid.Row="0" Grid.Column="0"  >
                        <StackLayout.GestureRecognizers>
                            <TapGestureRecognizer 
                                            Tapped="OnServerTapped" 
                                                NumberOfTapsRequired="1" />
                        </StackLayout.GestureRecognizers>
                        <Label Text="Server name" />
                        <Label x:Name="Server" Text="{Binding Connection}" />
                    </StackLayout>
                    <Label Text="{Binding UserName}" Grid.Row="1" Grid.Column="0"/>
                    <Label Text="{Binding Password}" Grid.Row="2" Grid.Column="0"/>
                    <StackLayout Orientation="Vertical" Grid.Row="3" Grid.Column="0" >
                        <Label Text="Test Connection" />
                        <Label Text="Click to test your connection settings" />
                    </StackLayout>
                </Grid>
                <Label Text="Location" />
                <Grid>
                    <Grid.RowDefinitions>
                        <RowDefinition Height="*" />
                        <RowDefinition Height="*" />
                    </Grid.RowDefinitions>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="***" />
                        <ColumnDefinition Width="*" />
                    </Grid.ColumnDefinitions>
                    <Label Text="Location Tracking" Grid.Row="0" Grid.Column="0" />
                    <Switch IsToggled="{Binding LocationTracking}" Grid.Row="0" Grid.Column="1" />
                    <StackLayout Orientation="Vertical" Grid.Row="1" Grid.Column="0">
                        <Label Text="Location Caching" />
                        <Label Text="WARNING! Experimental! Stores location data while offline." />
                    </StackLayout>
                    <Switch IsToggled="{Binding LocationCaching}" Grid.Row="1" Grid.Column="1" />
                </Grid>
                <Label Text="Logging Options" />
                <Grid>
                    <Grid.RowDefinitions>
                        <RowDefinition Height="*" />
                        <RowDefinition Height="*" />
                    </Grid.RowDefinitions>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="***" />
                        <ColumnDefinition Width="*" />
                    </Grid.ColumnDefinitions>
                    <StackLayout Orientation="Vertical" Grid.Row="0" Grid.Column="0">
                        <Label Text="Allow Logging" />
                        <Label Text="Collecting crash data" />
                    </StackLayout>
                    <Switch IsToggled="{Binding AllowLogging}" Grid.Row="0" Grid.Column="1" />
                    <StackLayout Orientation="Vertical" Grid.Row="1" Grid.Column="0">
                        <Label Text="Crash log email" />
                        <Label Text="Provide us an email to contact you regarding crash logs" />
                    </StackLayout>
                </Grid>
                <Label Text="Caching Options" />
                <Grid>
                    <Grid.RowDefinitions>
                        <RowDefinition Height="*" />
                        <RowDefinition Height="*" />
                    </Grid.RowDefinitions>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="***" />
                        <ColumnDefinition Width="*" />
                    </Grid.ColumnDefinitions>
                    <StackLayout Orientation="Vertical" Grid.Row="0" Grid.Column="0">
                        <Label Text="Caching" />
                        <Label Text="CacheSize:" />
                    </StackLayout>
                    <Switch IsToggled="{Binding Caching}" Grid.Row="0" Grid.Column="1" />
                    <StackLayout Orientation="Vertical" Grid.Row="1" Grid.Column="0">
                        <Label Text="Delete Cache" />
                        <Label Text="Click to delete the application cache" />
                    </StackLayout>
                </Grid>
                <Label Text="Updates" />
                <Grid>
                    <Grid.RowDefinitions>
                        <RowDefinition Height="*" />
                        <RowDefinition Height="*" />
                    </Grid.RowDefinitions>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="***" />
                        <ColumnDefinition Width="*" />
                    </Grid.ColumnDefinitions>
                    <Label Text="Notify me of new updates" Grid.Row="0" Grid.Column="0" />
                    <Switch IsToggled="{Binding UpdateNotify}" Grid.Row="0" Grid.Column="1" />
                    <Label Text="Check for updates" Grid.Row="1" Grid.Column="0" />
                </Grid>
            </StackLayout>
        </StackLayout>
    </ContentPage.Content>
</ContentPage>

这是背后的代码

using EIOBoardMobile.ViewModel;
using EIOBoardMobile.Views.popups;
using Rg.Plugins.Popup.Extensions;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace EIOBoardMobile.Views
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class SettingsPage : ContentPage
    {
        public SettingsPage ()
        {
            InitializeComponent ();
            BindingContext = new SettingsPageViewModel();
        }

        public async void OnServerTapped(object sender, EventArgs e)
        {
            await Navigation.PushPopupAsync(new ConnectionPopupPage());
        }
    }
}

和ViewModel

using EIOBoardMobile.Helpers;
using EIOBoardMobile.Model;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Text;
using System.Windows.Input;

namespace EIOBoardMobile.ViewModel
{
    public class SettingsPageViewModel : INotifyPropertyChanged
    {
        public ICommand ItemSelectedCommand { get; private set; }

        public SettingsPageViewModel()
        {

        }

        public void OnCreate()
        {

        }

        public string Connection
        {
            get { return Settings.ConnectionAddress; }
            set { Settings.ConnectionAddress = value; }
        }

        public string UserName
        {
            get { return Settings.UserName; }
            set { Settings.UserName = value; }
        }

        public string Password
        {
            get { return Settings.Password; }
            set { Settings.Password = value; }
        }

        public bool LocationTracking
        {
            get { return Settings.LocationTracking; }
            set { Settings.LocationTracking = value; }
        }

        public bool LocationCaching
        {
            get { return Settings.LocationCaching; }
            set { Settings.LocationCaching = value; }
        }

        public bool AllowLogging
        {
            get { return Settings.AllowLogging; }
            set { Settings.AllowLogging = value; }
        }

        public string CrashLogEmail
        {
            get { return Settings.CrashLogEmail; }
            set { Settings.CrashLogEmail = value; }
        }

        public bool Caching
        {
            get { return Settings.Caching; }
            set { Settings.Caching = value; }
        }

        public bool UpdateNotify
        {
            get { return Settings.UpdateNotify; }
            set { Settings.UpdateNotify = value; }
        }

        public event PropertyChangedEventHandler PropertyChanged;
        protected void RaisePropertyChanged(
            [CallerMemberName] string caller = "")
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(caller));
            }
        }
    }
}

知道我在做什么错吗？IDE未显示任何错误。我尝试设置OnTapped2种或3种不同方式的操作。我不能在StackLayout里面放一个Grid吗？任何帮助是极大的赞赏。