WPF Button in DataGrid/ListBox

I've encountered a problem when converting a WPF project from vs2008 to vs2010. I have a DataGrid that contains a ListBox. Each ListBoxItem has a Label and a Button. After converting to vs2010 the button no longer renders but crashes the app as soon as it comes into view. (Ie. the app loads but when the ListBox is created I get a NullReferenceException. What does work though is to remove the click event from the button and then it renders fine :) Same type of setup with Button within ListBoxItem also works when not inside a DataGrid. The content of ListBox obviously is meant to be dynamic but when working with a static collection I get the same error. Also removing the CommandParam does not help at all. Any pointers most welcome.

Code:

<DataGrid x:Name="DgTest" AutoGenerateColumns="false">
        <DataGrid.Columns>
            <DataGridTemplateColumn>
                <DataGridTemplateColumn.CellTemplate>
                    <DataTemplate>
                        <StackPanel>
                            <ListBox ItemsSource="{Binding ItemList}">
                                <ListBox.ItemTemplate>
                                    <DataTemplate >
                                        <StackPanel Style="{StaticResource hzp}">
                                            <Label  />
                                            <Button Click="Button_Click"     Content="TestButton"/>
                            开发者_如何学运维            </StackPanel>
                                    </DataTemplate>
                                </ListBox.ItemTemplate>
                            </ListBox>
                        </StackPanel>
                    </DataTemplate>
                </DataGridTemplateColumn.CellTemplate>
            </DataGridTemplateColumn>
        </DataGrid.Columns>
    </DataGrid>

Code-behind:

Imports System.Collections.ObjectModel

Class MainWindow
    Public TestList As New ObservableCollection(Of TestClass)

    Private Sub MainWindow_Loaded(ByVal sender As Object, ByVal e As     System.Windows.RoutedEventArgs) Handles Me.Loaded
    DgTest.ItemsSource = TestList
    TestList.Add(New TestClass(0))
    TestList.Add(New TestClass(1))
    End Sub

    Public Class TestClass
        Private _ItemList As New List(Of String)
        Private _id As Integer

        Public Property ItemList() As List(Of String)
        Get
            Return _ItemList
        End Get
        Set(ByVal value As List(Of String))
            _ItemList = value
        End Set
    End Property
    Public Property Id() As Integer
        Get
            Return _id
        End Get
        Set(ByVal value As Integer)
            _id = value
        End Set
    End Property


    Public Sub New(ByVal id As Integer)
        _ItemList.Add("String1")
        _id = id
    End Sub
End Class

Private Sub Button_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)

End Sub

End Class

And in App Resources:

<Style TargetType="StackPanel" x:Key="hzp">
        <Setter Property="Orientation" Value="Horizontal"/>
        <Setter Property="Background" Value="Orange"/>
</Style>

Now here's the strange thing. If the Stackpanel Style is removed, the button will work. If the Click event for the button is removed, it will load normally.

Seems like your event handler is gone from the code-behind file, check that first. Comment if that is not the case.

I believe I have found the answer to my own question. In the ListBox bound to an ObservableCollection all Styles must be DynamicResource. Using StaticResource worked well in 3.5 but not 4! Took a few hours of randomly testing everything to find this. Case closed