【WPF】Visibilityへのバインドで表示/非表示を制御する

表示、非表示を制御するのにVisibilityを使う方法があるけれど、ViewModelで設定したbool型をバインドするだけだとうまくいかない。
BooleanToVisibilityConverterも使ってバインドがうまくいく

■MainWindow.xaml
<Window x:Class="MyWorkProject.Views.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:prism="http://prismlibrary.com/"
        prism:ViewModelLocator.AutoWireViewModel="True"
        Title="{Binding Title}" Height="350" Width="525">
    <Window.Resources>
        <BooleanToVisibilityConverter x:Key="BoolVisibilityConverter" ></BooleanToVisibilityConverter>
    </Window.Resources>
    <Grid>
        <StackPanel>
            <Button Content="ボタンA"
                    Visibility="{Binding ButtonAVisibled, 
                        Converter={StaticResource BoolVisibilityConverter}}"/>
            <Button Content="ボタンB"
                    Visibility="{Binding ButtonBVisibled, 
                        Converter={StaticResource BoolVisibilityConverter}}"/>
            <ContentControl prism:RegionManager.RegionName="ContentRegion" />
        </StackPanel>
    </Grid>
</Window>

■MainWindowViewModel.cs
using Prism.Mvvm;

namespace MyWorkProject.ViewModels
{
    public class MainWindowViewModel : BindableBase
    {
        private string _title = "Prism Application";
        public string Title
        {
            get { return _title; }
            set { SetProperty(ref _title, value); }
        }

        private bool _buttonAVisibled;
        public bool ButtonAVisibled
        {
            get { return _buttonAVisibled; }
            set { SetProperty(ref _buttonAVisibled, value); }
        }

        private bool _buttonBVisibled;
        public bool ButtonBVisibled
        {
            get { return _buttonBVisibled; }
            set { SetProperty(ref _buttonBVisibled, value); }
        }

        public MainWindowViewModel()
        {
            ButtonAVisibled = true;
            ButtonBVisibled = false;
        }
    }
}