Managed C++ Error when using a snk file:: "missing the private key needed for signing"

Why am I getting this error when trying to sign a Managed C++ project using a .snk file. "......SlimDX\build\vs2010\x86\Debug\VOS.snk' is missing the private key needed for signing"

Iv'e tried setting it in the project settings::

1. Key File = $(ProjectDir)x86\$(Configuration)\VOS.snk
2. Delay Sign = No (/DELAYSIGN:NO)

And iv'e tried setting it in AssemblyInfo.cpp::

1. [assembly:AssemblyKeyFile("VOS.snk")]
2. [assembly:AssemblyDelaySignAttribute(false)]

I have both the .snk & .pfx files. What am I missing here? The .snk file is all I need in my C# .NET 3.5 project... Why will it not work in my managed c++ project as well? Do I need to use my pfx file also in some way?

Well somehow I was using a corrupt key or something, because when I got a new .snk file it all worked the way it should....