Creating NuGet Packages - Why doesn't this folder structure work for .NET 4.0?

Here is the issue I'm having - I cannot get my project's NuGet package to work for .NET 4.0.

Here is what my folder structure looks like:

 lib\   
      \.NET 4.0
          binary.dll   
      \Silverlight 4.0
          binary.silverlight.dll

Whenever I try to add this package to a Silverlight 4 project, it work开发者_如何学JAVAs just fine. When I try to add it to an ASP.NET MVC3 app I get the following error: "unable to find assembly references that are compatible with the target framework '.NETFramework, version=v4.0'"

What am I doing wrong?

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Change the folder name to Net40 and SL4 (or Silverlight4 no spaces). You should file a bug though, those names should work. I think the "." in .NET might be throwing it off.