为什么我的视图不能识别来自视图模型的电子邮件和密码字符串。它说电子邮件和密码在当前上下文中不存在。有人能告诉我为什么这段代码不起作用并解释解决方案吗？这是视图中的代码：

using System;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
using Papucometar.ViewModel;
using Xamarin.Essentials;
namespace Papucometar.View
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class LoginUI : ContentPage
    {
        public LoginUI()
        {
            var vm = new LoginViewModel();
            this.BindingContext = vm;
            vm.DisplayInvalidLoginPrompt += () => DisplayAlert("Error", "Invalid Login, try again", "OK");
            InitializeComponent();

            email.Completed += (object sender, EventArgs e) =>
            {
                Password.Focus();
            };

            Password.Completed += (object sender, EventArgs e) =>
            {
                vm.SubmitCommand.Execute(null);
            };
        }
    }
}

这是ViewModel代码：

using System.ComponentModel;
using System.Text;
using System.Windows.Input;
using Xamarin.Essentials;
using Xamarin.Forms;

namespace Papucometar.ViewModel
{
    public class LoginViewModel : INotifyPropertyChanged
    {
        public Action DisplayInvalidLoginPrompt;
        public event PropertyChangedEventHandler PropertyChanged = delegate { };
        private string Email;
        public string email
        {
            get { return Email; }
            set
            {
                Email = value;
                PropertyChanged(this, new PropertyChangedEventArgs("Email"));
            }
        }
        private string password;
        public string Password
        {
            get { return password; }
            set
            {
                password = value;
                PropertyChanged(this, new PropertyChangedEventArgs("Password"));
            }
        }
        public ICommand SubmitCommand { protected set; get; }
        public LoginViewModel()
        {
            SubmitCommand = new Command(OnSubmit);
        }
        public void OnSubmit()
        {
            if (email != "macoratti@yahoo.com" || password != "secret")
            {
                DisplayInvalidLoginPrompt();
            }
        }
    }
}

IntelliSense说这些变量不存在。我不明白为什么它们不能互相看到。这是xaml代码

<?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="Papucometar.View.LoginUI"
             xmlns:local="clr-namespace:Papucometar.ViewModel"
             x:DataType="local:LoginViewModel"
             BackgroundColor="#112B47">
    <ContentPage.Content>  
    <StackLayout Orientation="Vertical" Padding="30" Spacing="40">  
        <BoxView HeightRequest="10"/>  
        <Image HorizontalOptions="Center" WidthRequest="300" Source="maco.jpg"/>  
        <Frame BackgroundColor="#BF043055" HasShadow="False">  
            <StackLayout Orientation="Vertical" Spacing="10">  
                <Entry x:Name="Email" Text="{Binding Email}" Placeholder="Email"   
                       PlaceholderColor="White" HeightRequest="40"   
                       Keyboard="Email"  
                       TextColor="White"/>  
                <Entry x:Name="Password" Text="{Binding Password}" Placeholder="Senha"   
                       PlaceholderColor="White" HeightRequest="40"   
                       IsPassword="True"  
                       TextColor="White"/>  
            </StackLayout>  
        </Frame>  
        <Button Command="{Binding SubmitCommand}" Text="Login" TextColor="White"  
                FontAttributes="Bold" FontSize="Large" HorizontalOptions="FillAndExpand"  
                BackgroundColor="#088da5" />  
    </StackLayout>  
</ContentPage.Content>  
</ContentPage>