Strange assembly issue using WESTWIND globalization

Question

I'm using Visual Studio 2010 Ultimate with version 4.0 of the .NET Framework.

I'm attempting globalization for a website using the free westwind globalization dll.

I add the Westwind.Web assembly

then its two dependencies: Westwind.Globalization and Westwind.Utilities

Initially, after adding the assemblies the objects are recognized (turn green in VS) but when i rebuild i get an error:

The type or namespace name 'Westwind' could not be found (are you missing a using directive or an assembly reference?)

i've tried copying the assemblies to my project folder as well as the bin folder and adding them again, but i get the same issue. Has anyone experienced a similar issue?