Trouble with ResourceDictionary (Lazy access?)

Hello,

I'm having trouble with my ResourceDictionary. I have a generic.xaml (Build Action=Page)

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:my="clr-namespace:siemens.CSharp.JobManagement"
                    x:Class="IPIPEResourceDictionary"><ResourceDictionary.MergedDictionaries><ResourceDictionary Source="/siemens.CSharp;component/themes/buttons.xaml"/><ResourceDictionary Source="/siemens.CSharp;component/themes/colors.xaml"/><ResourceDictionary Source="/siemens.CSharp;component/themes/controls.xaml"/></ResourceDictionary.MergedDictionaries><Color x:Key="TEST">#25254E</Color></ResourceDictionary>

all other ResourceDictionaries are set to Build Action=Content.

The AssemblyInfo.cs has following entry

[assembly: ThemeInfo(ResourceDictionaryLocation.None, ResourceDictionaryLocation.SourceAssembly)]

In one of the resource dictionaries I have a Style

<Style TargetType="{x:Type my:IPIPEStatusSideBarView}"><Setter Property="Height" Value="150"/><Setter Property="Width" Value="350"/><Setter Property="Margin" Value="350,0,0,0"/><Setter Property="Background" Value="#65658E"/>

and I have a control that overrides the style key:

public class IPIPEStatusSideBarView : UserControl
	{
		static IPIPEStatusSideBarView()
		{
			DefaultStyleKeyProperty.OverrideMetadata(typeof(IPIPEStatusSideBarView), new FrameworkPropertyMetadata(typeof(IPIPEStatusSideBarView)));

			//GetDefaultStyle()));
		}

The problem is, that the style never gets applied. I have done some testing a found an interesting thing:

var foo = new Uri("Themes/generic.xaml", UriKind.RelativeOrAbsolute);
			ResourceDictionary dict = new ResourceDictionary();

			dict.BeginInit();
			dict.Source = foo;
			dict.EndInit();


			Style = dict["TEST"] as Style;
			Style = dict[typeof(IPIPEStatusSideBarView)] as Style;
			Style = dict[typeof(IPIPEStatusSideBarView)] as Style;

If I access "TEST" it gives my the value immediately. If I access IPIPEStatusSideBarView I get the value only the second time. If I put it one level up into the main dictionary, it works immediately.

What could be wrong. Why is it loaded in some lazy way?

Thanks

Martin

msedi