HierarchicalDataTemplate problem

Question

Hi i am building a user control in wpf and using a treeview, then using the HierarchicalDataTemplate to load the parts of the treeview using a Class called Node.

<TreeView Name="T">

    <TreeView.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="OrgChartTreeViewItemStyle.xaml" />
            </ResourceDictionary.MergedDictionaries>
            <HierarchicalDataTemplate 
                DataType="{x:Type local:Node}"
                ItemsSource="{Binding ChildNodes}">
                <TextBlock Text="{Binding Text}"/>
            </HierarchicalDataTemplate>
        </ResourceDictionary>
    </TreeView.Resources>

    <TreeView.ItemsPanel>

        <ItemsPanelTemplate>
            <Grid 
      HorizontalAlignment="Center" 
      IsItemsHost="True" />
        </ItemsPanelTemplate>
    </TreeView.ItemsPanel>

</TreeView>

This works perfectly but when i tried to add the userControl to a usercontrol to display the tree i got the next error.

I already check the assembly using the ildams an it is including the node Class ..

Any thougths ??

Thanks