Commented Unassigned: Faild to build .net 4 targeted app [331]

Hi. I'm working on a project, using `VS 2012` running on `Windows 8` that targets `.NET 4`. I compiled it in `Debug` mode, and copy/paste it to a machine that runs `Windows 7` and have installed `.NET 4`. But when I try to run the app, it crashed. After a while, I figured out that I have to install `.NET 4.5` on target machine; while there is no dependency to `.NET 4.5` in my project -it's really a simple app.
Then, I tried to compile the app to release version. When I changed the configuration in vs from `Debug` to `Release` , the project cannot be build at all. I get this error:

> The type 'Caliburn.Micro.PropertyChangedBase' is defined in an assembly that is not referenced. You must add a reference to assembly 'Caliburn.Micro, Version=1.5.1.0, Culture=neutral, PublicKeyToken=8e5891231f2ed21f'.


while the project references to `Caliburn.Micro`. Any idea?
Comments: I use CM with NuGet and .NET 4.0 in VS2012 and I cannot reproduce this kind of behavior. Are you sure the project targets .NET 4.0? It seems to me that your projects targets .NET 4.5 instead... Regarding the Release compilation issue, I have not tested it, but as far as I know, NuGet has no support (at least at the moment) for Debug/Release dlls, so the reference should be the same.