This is what I have in my Exec Directories:
$(VC_ExecutablePath_x64)
$(WindowsSDK_ExecutablePath)
$(VS_ExecutablePath)
$(MSBuild_ExecutablePath)
$(FxCopDir)
$(PATH)
What is in your NMAKE Include Search Path?
What are your Solution Platform and Config? (For example, my current settings whilst debugging is: Win64 and Debug Game Editor)