Your XAML is wrong. This is the right way to merge ResourceDictionaries:
<UserControl.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="AllOrdersViewResources.xaml"/>
</ResourceDictionary.MergedDictionaries>
<!-- More resources here -->
</ResourceDictionary>
</UserControl.Resources>