当前不存在吗？

Question

我的xaml.cs页面未在Mainpage.xaml类中获得按钮的“ x：name”，有人知道为什么我会收到此错误吗？我是Xamarin的新手，我真的不知道自己在做什么，我将在下面发布代码。 谢谢你一百万！！！！

MainPage.xaml：

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:VideoPlayer"
             xmlns:forms="clr-            
             namespace:Plugin.MediaManager.
             Forms;assembly=Plugin.MediaManager.Forms"
             x:Class="VideoPlayer.MainPage">

    <StackLayout>
        <forms:VideoView WidthRequest="360"
                         HeightRequest="202"
                     />
        <Button x:Name ="PlayStop"
                Text="Play"
                Clicked= "Button_Clicked">



        </Button>




    </StackLayout>

</ContentPage>

xaml.cs:
using Plugin.MediaManager;
using Plugin.MediaManager.Abstractions.Enums;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;

namespace VideoPlayer
{
    public partial class MainPage : ContentPage
    {
        String videoUrl = "https://www.youtube.com/watch?v=kZ-eFt5kSSQ";
        public MainPage()
        {

            InitializeComponent();
        }

        private void PlayStop_Clicked(object sender, EventArgs e)
        {
            if (PlayStop.Text == "Play")
            {
              CrossMediaManager.Current.Play(videoUrl,MediaFileType.Video);
            };
        }
    }
}