Generic.XAML template not properly applied in custom control

Hi,

I created a custom control deriving from ContextMenu in VB.net language.

It's default style is defined in the Generic.XAML being in the same assembly as the custom control. To configure this I added this line to the AssemblyInfo.vb:

<Assembly: ThemeInfo(ResourceDictionaryLocation.None, ResourceDictionaryLocation.SourceAssembly)> 

In the controls shared(static) constructor I said that the control has it's own control style:

DefaultStyleKeyProperty.OverrideMetadata(GetType(FilterContextMenu), New FrameworkPropertyMetadata(GetType(FilterContextMenu)))

I added a test project (VB.net) to the solution, referenced the assembly of the control, added namespaces, etc and it works. The visual tree in the WPF tree visualizer looks like this:

But when I reference the custom control assembly in another solution (C# language) the visual tree gets broken and looks like this:

The controls default style in the generic.xaml looks like this.

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:cv="clr-namespace:DataGridContextMenuFilter.Converter"
                    xmlns:local="clr-namespace:DataGridContextMenuFilter.FilterControls"><cv:InvalidDateToNullConverter x:Key="InvalidDateToNullConverter" /><cv:InvalidBooleanToNullConverter x:Key="InvalidBooleanToNullConverter" /><Style TargetType="{x:Type local:FilterContextMenu}"><Setter Property="SnapsToDevicePixels" Value="True" /><Setter Property="Grid.IsSharedSizeScope" Value="true" /><Setter Property="HasDropShadow" Value="True" /><Setter Property="Template"><Setter.Value><ControlTemplate TargetType="local:FilterContextMenu"><Menu Name="FilterMenu"><Menu.ItemsPanel><ItemsPanelTemplate><VirtualizingStackPanel Orientation="Vertical" /></ItemsPanelTemplate></Menu.ItemsPanel><TextBox Name="CriteriaValue" Text="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType=local:FilterContextMenu, AncestorLevel=1}, Path=CriteriaValue, UpdateSourceTrigger=PropertyChanged}" /><DatePicker Name="CriteriaValueDate" SelectedDate="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType=local:FilterContextMenu, AncestorLevel=1}, Path=CriteriaValue, UpdateSourceTrigger=PropertyChanged, Converter={StaticResource InvalidDateToNullConverter}}" /><ComboBox Name="CriteriaValueEnum"
                                  DisplayMemberPath="{Binding RelativeSource={RelativeSource FindAncestor,
                                                                                             AncestorType=local:FilterContextMenu,
                                                                                             AncestorLevel=1},
                                                              Path=DisplayMemberPath,
                                                              UpdateSourceTrigger=PropertyChanged}"
                                  ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor,
                                                                                       AncestorType=local:FilterContextMenu,
                                                                                       AncestorLevel=1},
                                                        Path=CriteriaValueList,
                                                        UpdateSourceTrigger=PropertyChanged}"
                                  SelectedItem="{Binding RelativeSource={RelativeSource FindAncestor,
                                                                                        AncestorType=local:FilterContextMenu,
                                                                                        AncestorLevel=1},
                                                         Path=CriteriaValue,
                                                         UpdateSourceTrigger=PropertyChanged}" /><CheckBox Name="CriteriaCheckBox"
                                  IsChecked="{Binding RelativeSource={RelativeSource FindAncestor,
                                                                                     AncestorType=local:FilterContextMenu,
                                                                                     AncestorLevel=1},
                                                      Path=CriteriaValue,
                                                      UpdateSourceTrigger=PropertyChanged,
                                                      Converter={StaticResource InvalidBooleanToNullConverter}}"
                                  IsThreeState="True" /><TextBlock Name="FilterNotAvailable"
                                   Width="200"
                                   Text="{Binding RelativeSource={RelativeSource FindAncestor,
                                                                                 AncestorType=local:FilterContextMenu,
                                                                                 AncestorLevel=1},
                                                  Path=FilterNotAvailableMessage,
                                                  UpdateSourceTrigger=PropertyChanged}"
                                   TextWrapping="Wrap" /><ListBox Name="CompareOperationList"
                                 Width="200"
                                 ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor,
                                                                                      AncestorType=local:FilterContextMenu,
                                                                                      AncestorLevel=1},
                                                       Path=CompareOperations,
                                                       Mode=TwoWay,
                                                       UpdateSourceTrigger=PropertyChanged}"><ListBox.ItemContainerStyle><Style TargetType="ListBoxItem"><Style.Triggers><Trigger Property="IsMouseOver" Value="True"><Setter Property="Background" Value="LightGray" /></Trigger></Style.Triggers></Style></ListBox.ItemContainerStyle></ListBox><local:FilterButton x:Name="RemoveFilterButton"
                                            Content="Remove filter"
                                            IsEnabled="{Binding RelativeSource={RelativeSource FindAncestor,
                                                                                               AncestorType=local:FilterContextMenu,
                                                                                               AncestorLevel=1},
                                                                Path=GroupFilter.IsFilterActive}" /><ItemsPresenter />  </Menu></ControlTemplate></Setter.Value></Setter></Style></ResourceDictionary>

Any idea why the control's visual tree gets broken would be great.

Thank you!