无法在矩形区域WPF C＃中拖动放置文件或文件夹

Question

这是我的XAML

<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="8*"/>
        <RowDefinition Height="*"/>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>

    <ProgressBar Grid.Row="1" IsIndeterminate="False" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Foreground="#02F4C4" Value="{Binding CurrentProgress}"/>
    <TextBlock Grid.Row="1" Text="{Binding CurrentProgressText}" HorizontalAlignment="Center" VerticalAlignment="Center" FontSize="22"/>

    <ProgressBar Grid.Row="2" IsIndeterminate="False" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Foreground="#02F432" Value="{Binding OverallProgress}"/>
    <TextBlock Grid.Row="2" Text="{Binding OverallProgressText}" HorizontalAlignment="Center" VerticalAlignment="Center" FontSize="22"/>

    <Rectangle Grid.Row="0" Fill="#CCCCCC" HorizontalAlignment="Stretch" Stroke="Black" VerticalAlignment="Stretch" AllowDrop="True" DragOver="Rectangle_DragOver" Drop="Rectangle_Drop" DragEnter="Rectangle_DragOver" Visibility="{Binding DragDropVisibility}"/>
    <TextBlock Grid.Row="0" Text="Drag folder(s) here to start" VerticalAlignment="Center" HorizontalAlignment="Center" FontSize="20" AllowDrop="True" DragOver="Rectangle_DragOver" Drop="Rectangle_Drop" DragEnter="Rectangle_DragOver" Visibility="{Binding DragDropVisibility}"/>
</Grid>

并且我试图将文件/文件夹拖到该矩形区域，但是没有成功意味着在Rectangle_DragOver上没有断点：

private void Rectangle_DragOver(object sender, DragEventArgs e)
{
    //e.Effects = DragDropEffects.None;

    if (e.Data.GetDataPresent(DataFormats.FileDrop))
    {
        var files = e.Data.GetDataPresent(DataFormats.FileDrop);

        e.Effects = DragDropEffects.Copy | DragDropEffects.Move;
    }
}

private void Rectangle_Drop(object sender, DragEventArgs e)
{

}

我的错误在哪里？怎么了？