PropertyMetadata is already registered

Hi all of you,

I've got a class with one property but it is not visible from my view and have not idea why...main problem here I got a couple of errors:

"Instance coud not created BotoEspecial"

And then:

"PropertyMetadata is already registered for BotoEspecial type"

My Vb class:

Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports System.Text
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Data
Imports System.Windows.Documents
Imports System.Windows.Input
Imports System.Windows.Media
Imports System.Windows.Media.Imaging
Imports System.Windows.Navigation
Imports System.Windows.Shapes
Imports System.Windows.Controls.Primitives
Public Class BotoEspecial
    Inherits ButtonBase

    Public Sub New()
        DefaultStyleKeyProperty.OverrideMetadata(GetType(BotoEspecial), New FrameworkPropertyMetadata(GetType(BotoEspecial)))
    End Sub
 Public Property IconImage() As BitmapImage
        Get
            Return DirectCast(GetValue(IconImageProperty), BitmapImage)
        End Get
        Set(value As BitmapImage)
            SetValue(IconImageProperty, value)
        End Set

    End Property
    Public Shared ReadOnly IconImageProperty As DependencyProperty = _
        DependencyProperty.Register("IconImage", GetType(BitmapImage), GetType(BotoEspecial), New UIPropertyMetadata(Nothing))

End Class

My whole view (window):

<Window x:Class="SeleccionMarca"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:GIT_CuadroMando"
    Title="SeleccionMarca" Height="345.802" Width="753.435"><Grid Margin="0,0,2,-3"><StackPanel Orientation="Horizontal" VerticalAlignment="Top" Margin="10,10,10,0" Height="299"/><local:BotoEspecial.IconImage></local:BotoEspecial.IconImage><BitmapImage UriSource="/Imagenes/Logos Marcas/BMW_31.jpg"/></local:BotoEspecial.IconImage></Grid></Window>

Thanks in advance for any hint,

Primary platform is Windows 7 Ultimate 64 bit along with VS 2012/Sql2k8 for WPF and SilverLight stuff