'Set property 'System.Windows.ResourceDictionary.Source' threw an exception.

Application x:Class="FortySixApplesResourceDictionaryDemo.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             StartupUri="MainWindow.xaml">
    <Application.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="pack://application:,,,/Demo.Common;component/Resource Dictionaries/MacStyledWindow.xaml" />


            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </Application.Resources>
</Application>