WPF KeyBindings无效

Question

已经讨论了十几个或更多有关此主题的SO问题和文章。似乎没什么用。这是我的简单系统。主Window，其中包含Frame个主机Page个对象。我的一个Page对象中包含以下内容：

<Page.Resources>
    <RoutedUICommand x:Key="PreviousRecordCommand" Text="Previous Record" />
    <RoutedUICommand x:Key="NextRecordCommand" Text="Previous Record" />

    <CollectionViewSource x:Key="cvsAllOrders" Source="{Binding AllSalesOrders}" />
</Page.Resources>

<Page.CommandBindings>
    <CommandBinding Command="{StaticResource PreviousRecordCommand}" Executed="PreviousRecordCommand_Executed" CanExecute="PreviousRecordCommandBinding_CanExecute" />
    <CommandBinding Command="{StaticResource NextRecordCommand}" Executed="NextRecordCommand_Executed" CanExecute="NextRecordCommandBinding_CanExecute" />
</Page.CommandBindings>

<Page.InputBindings>
    <KeyBinding Command="{StaticResource PreviousRecordCommand}" Gesture="CTRL+LEFT" />
    <KeyBinding Command="{StaticResource NextRecordCommand}" Gesture="CTRL+RIGHT" />
</Page.InputBindings>

代码隐藏有：

Private Sub PreviousRecordCommand_Executed(sender As System.Object, e As System.Windows.Input.ExecutedRoutedEventArgs)
    Dim CurView = DirectCast(Me.Resources("cvsAllOrders"), CollectionViewSource).View
    CurView.MoveCurrentToPrevious()
    If CurView.IsCurrentBeforeFirst Then CurView.MoveCurrentToFirst()
End Sub

Private Sub NextRecordCommand_Executed(sender As System.Object, e As System.Windows.Input.ExecutedRoutedEventArgs)
    Dim CurView = DirectCast(Me.Resources("cvsAllOrders"), CollectionViewSource).View
    CurView.MoveCurrentToNext()
    If CurView.IsCurrentAfterLast Then CurView.MoveCurrentToLast()
End Sub

Private Sub PreviousRecordCommandBinding_CanExecute(sender As System.Object, e As System.Windows.Input.CanExecuteRoutedEventArgs)
    Dim MyView = DirectCast(Me.Resources("cvsAllOrders"), CollectionViewSource).View
    e.CanExecute = (MyView IsNot Nothing) AndAlso (DirectCast(Me.Resources("cvsAllOrders"), CollectionViewSource).View.CurrentPosition > 0)
End Sub

Private Sub NextRecordCommandBinding_CanExecute(sender As System.Object, e As System.Windows.Input.CanExecuteRoutedEventArgs)
    Dim MyView = DirectCast(Me.Resources("cvsAllOrders"), CollectionViewSource).View
    e.CanExecute = (MyView IsNot Nothing) AndAlso (DirectCast(Me.Resources("cvsAllOrders"), CollectionViewSource).View.CurrentPosition < DirectCast(Me.Resources("cvsAllOrders"), CollectionViewSource).View.Cast(Of SalesOrderEntryModel.SalesOrder).Count() - 1)
End Sub

我无法让这个工作。我也试过在我的代码隐藏中声明命令。没有任何区别。作为参考，我在Page上有几十个文本框和其他控件，需要这些键才能在当前焦点的任何位置工作。

非常感谢任何帮助。