Could not load file or assembly 'WPF.MDI, Version=1.1.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies

Using WPF.MDI dll from codeplex in my wpf project I am getting this error when I run the project:

Could not load file or assembly 'WPF.MDI, Version=1.1.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. A strongly-named assembly is required. 
(Exception from HRESULT: 0x80131044)":"WPF.MDI, Version=1.1.0.0, Culture=neutral, PublicKeyToken=null

I discovered it happens when I add name to the MdiContainer:

 <mdi:MdiContainer Theme="Aero" DockPanel.Dock="Top" Margin="0 20 0 0" Name="MainMdiContainer">

But I need the name to call the child into the MdiContainer.