How to export to wind 8...getting error.

I have windows 8.1 and latest unity 4.5. I have a game that I can export out to android, windows 86 and 64 bit, and other platforms. However, I am having a issue exporting to windows 8 or 8.1. It gives me errors. It may have to do with the SDK.

1) Can someone give a list of what needs to be imported and installed to export to win 8. 2) any ideas of what the issue is? I though I installed everything I was supposed to.

================ Could not start compilationException: 'References\CommonConfiguration\Neutral\Windows.winmd' not found, do you have Windows 8.0 SDK installed? UnityEditor.Scripting.Compilers.MicrosoftCSharpCompiler.FillNETCoreCompilerOptions (MetroSDK metroSDK, System.Collections.Generic.List`1 arguments, System.String& argsPrefix) (at C:/BuildAgent/work/d63dfc6385190b60/Editor/Mono/Scripting/Compilers/MicrosoftCSharpCompiler.cs:134) UnityEditor.Scripting.Compilers.MicrosoftCSharpCompiler.StartCompiler () (at C:/BuildAgent/work/d63dfc6385190b60/Editor/Mono/Scripting/Compilers/MicrosoftCSharpCompiler.cs:225) UnityEditor.Scripting.Compilers.ScriptCompilerBase.BeginCompiling () (at C:/BuildAgent/work/d63dfc6385190b60/Editor/Mono/Scripting/Compilers/ScriptCompilerBase.cs:47)

Compilation failed because the compiler couldn't be executed!

Error building Player because scripts had compiler errors