It should be set to “C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\Tools” (assuming that actually exists depending on where you installed it).
I meant that following should be a valid path (for VS2013 Express anyway): “%VS120COMNTOOLS%/…/IDE/WDExpress.exe”
So to resolve that out: “C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7/…/IDE/WDExpress.exe”
And to collapse it down: “C:\Program Files (x86)\Microsoft Visual Studio 12.0\IDE\WDExpress.exe”