New Post: OnPropertyChanged not fired when SetProperty is called

I have created a new VB project (named TestPrismVB), installed Prism and I have written this simple code:

Imports Microsoft.Practices.Prism.Mvvm

Public Class pruebaViewModel
    Inherits BindableBase

    Private Property _oneProperty As String
    Public Property oneProperty As String
        Get
            Return _oneProperty
        End Get
        Set(value As String)
            SetProperty(_oneProperty, value)
            'IF I UNCOMMENT THIS LINE, IT WORKS:
            'OnPropertyChanged("oneProperty")
        End Set
    End Property

    Private Property _anotherProperty As String
    Public Property anotherProperty As String
        Get
            Return _anotherProperty
        End Get
        Set(value As String)
            SetProperty(_anotherProperty, value)
            oneProperty = value
        End Set
    End Property
End Class
And the XAML file is MainWindow.xaml:

<Window x:Class="MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:vm="clr-namespace:TestPrismVB"
    Title="MainWindow" Height="350" Width="525">
    <Window.DataContext>
        <vm:pruebaViewModel/>
    </Window.DataContext>
    <StackPanel>
        <TextBox Text="{Binding anotherProperty, UpdateSourceTrigger=PropertyChanged}"/>
        <TextBlock Text ="{Binding oneProperty}"/>
    </StackPanel>
</Window>

If you run this simple project, and you type 1234, you will see that the TextBlock updates one step behind (it will show 123 instead of 1234).

Is it a VB bug? A Prism bug? Am I doing something wrong?

Thank you