epalm Nov 26, 2010 at 2:38 PM Sorry for I'm sure will be a silly question but... I've downloaded the .NET 4 dll files, referenced them in my project, things are actually working well.  However, Visual Studio 2010 complains when I use the AvalonDock controls:       The above xaml file produces this error: Error 1 The type 'ad:DockingManager' was not found. Verify that you are not missing an assembly reference and that all referenced assemblies have been built. C:\path\to\MainWindow.xaml 18 10 MyWPFProject And the designer view says: Problem Loading. The document contains errors that must be fixed before the designer can be loaded. Reload the designer after you have fixed the errors. The weird part is everything compiles and runs fine.  How do I get the Visual Studio 2010 xaml designer to play nice? (Note: when I open up the samples in VS2010 they work fine, no errors) nez7 Jan 5, 2011 at 12:12 PM Even I am facing a similar problem. I have downloaded both ver1.2 and ver1.3. When I run the sample projects, they don't compile. I get an error that DockingManager was not found. I am new to both WPF and avalondock. I really need to take a look into the sample projects to see how to use avalondock for getting VisualStudio like docking capabilities. Please help. mprevot Jun 2, 2012 at 3:34 PM In the error message VS2010 suggests that you visit http://msdn.microsoft.com/en-us/library/ee890038%28VS.100%29.aspx unagarajan Jul 23, 2013 at 9:12 PM Thanks. "Unblock"ing really helped.