有人能告诉我为什么绑定在这里不起作用吗？我试图将这个字符串CountDisplay绑定到标签文本，但它说没有数据上下文，我发现这是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.Views.Skener"
             BackgroundColor="White">
    <Grid RowDefinitions="*,Auto,Auto,*">
        <Label
                Grid.Row="1"
                FontSize="Large"
                HorizontalOptions="Center" 
                Text="{Binding CountDisplay}"/>
        <Button 
            x:Name="ButtonCount"
            Grid.Row="2"
            Text="Click me"
            Clicked="ButtonClicked_Clicked"
            />
    </Grid>
</ContentPage>

下面是代码：

`using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

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

namespace PapucoMetar.Views
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class Skener : ContentPage
    {
        public Skener()
        {
            InitializeComponent();
            BindingContext = this;
        }
        int count = 0;
        string countDisplay = "Click me";
        public string CountDisplay
        {
            get => countDisplay;
            set
            {
                if (value == countDisplay)
                    return;
                countDisplay = value;
                OnPropertyChanged();
            }
        }
        private void ButtonClicked_Clicked(object sender, EventArgs e)
        {
            count++;
            CountDisplay = $"You clicked button {count} time(s)";
        }

    }
}`

我试图绑定按钮的点击次数，但由于某种原因，它不能识别字符串计数显示。