Can't create xmlns reference to other project in XAML

I have a WPF project defined like this:

MyApp.sln
  MyAppWPF
  MyApp.Domain

In one of my xaml files in the MyAppWPF project I'm trying to reference a class defined in MyApp.Domain project. I have a project reference in MyAppWPF to MyApp.Domain. I am trying to create the reference like this:

<Window x:Class="MyAppWPF.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:MyApp.Domain;assembly=MyApp.Domain"
    Title="Window1" Height="305" Width="485">
    <Window.Resources>
       <local:MyClass x:Key="mine" />
    </Window.Resources>
</Window>

I get an error saying the assembly cannot be found, however I can create an instance of the class I want to reference in the code behind, so I know I've got it referenced correctly.

How do I do this? Do I need a strong name, or reference the dll directly instead of using a project reference?

From stackoverflow

• Check if

  1. the fully qualified name for MyClass is MyApp.Domain.MyClass
  2. MyClass has a default public constructor (with no parameters) so that XAML can instantiate it.

• Could be of any help?
  
  Visual Studio 2008 (RTM) WPF Designer Could Not Load Assembly or Dependency

  I assume you are using Visual Studio 2008. If you are using Visual Studio 2005, this is a known issue in the XAML designer code-named "Cider", which is included in the "Visual Studio 2005 Extensions for WPF and WCF".

• If the XAML is not loose (is compiled within an assembly (DLL/EXE)
  make sure that assembly has a reference to the assembly you are looking for
  (right click on the project --> add reference ...).
  
  If the XAML is loose, make sure the assembly it is looking for is copied to the same directory the exe is ran from.