Resource can't be found even when it's present - asp.net

Question

I've got a really weird issue I can't fix within a Wpf Application. We built a Common Library containing many useful components, one of them is a fancy MessageBox which has the company style. There're three dictionaries that contains nearly everything we require:
<ResourceDictionary Source="/Library;component/Style/Styles.xaml" />
<ResourceDictionary Source="/Library;component/Themes/Globals.xaml"/>
<ResourceDictionary Source="/Library;component/Themes/Controls/Button/Template.xaml"/>
There's a footer for the MessageBox into Globals.xaml, footer uses a template from Template.xaml. It works perfectly but not in one case. I have a main window that dinamically create a plugin and open a window. This window is a regular Window Wpf application loaded through reflection.
Method to open MessageBox is within the same DLL as Resource Dictionaries.
If I call this MessageBox method from the plugin it throws an exception because "Footer" is not found. I set a breakpoint before
window.ShowDialog();
And I see MergedDictionaries is empty into window. Also empty everywhere, only owner of this MessageBox contains those resources. Doing
window.FindResource("key");
Get a null value as expected. However, if I manually copy merged dictionaries using this code lines before open dialog:
foreach (var dict in owner.Resources.MergedDictionaries)
{
window.Resources.MergedDictionaries.Add(dict);
}
And then look for window.FindResource("key") I can see the style, but even though it continues throwing an exception:
Cannot find resource named '{Footer}'. Resource names are case sensitive.
Footer style is used in this line of MessageBox:
<StatusBar Style="{StaticResource Footer}" DataContext="{Binding ElementName=window}"...
I've also tried to declare this resource into the DialogWindow in the library, even when I've not gonna be allowed to change it:
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="/Library;component/Themes/Generic.xaml" />
<ResourceDictionary Source="/Library;component/Themes/Globals.xaml"/>
<ResourceDictionary Source="/Library;component/Themes/Controls/Button/Template.xaml"/>
</ResourceDictionary.MergedDictionaries>
I've been 2 days knocking my head on the monitor and nothing, everything I tried failed. Despite of breaking a monitor of course.
Ran out of ideas...
Regards.

Answer 1

Make sure of the following things
The resource dictionary Build Action is set to Page
Every project that references the Style has a library reference to it (Even if you put the Dictionary in App.xaml if a project that doesn't reference the Resources Library then it wont find it
Place the MergedDictionaries in App.xaml (or in the specific page you want to use them)