WPF assembly reference missing - project still building

An additional point for other readers: if you projects builds successfully, but you get this error message while trying to load your view in the designer, make sure your assembly is x86 or Any CPU, because Visual Studio 2010 is a 32bit process and cannot load x64 assemblies in the designer.

This appears to be a schema reference, not an assembly reference.

Something like this might work better:

xmlns:d3="clr-namespace:Microsoft.Research.DynamicDataDisplay;assembly=DynamicDataDisplay"

http://msdn.microsoft.com/en-us/library/ms747086.aspx

Edit

I think I found the library you are using, so I updated the XAML namespace reference to what I think will work for you. If not, check the docs, or start editing some code, and figure out the namespace that the ChartPlotter class lives in.

I got the same "Unable to load metadata" error when referencing the DLL file found in binary version of Dynamic Data Display Library. The problem was solved when I downloaded the source version of the library and compiled it myself. When referencing the DLL under DynamicDataDisplay_0.3/sln/DynamicDataDisplay/Debug/bin , it worked just fine.

I suppose the problem is with some permissions of the DLL, as pointed already at the end of the question - you can "unblock it", see above.