I’m starting to get reports about Windows 8.1 compatibility with the latest version of DPack for VS 2012. Looks like Microsoft had changed the internal .NET version shipping with Windows 8.1 RTM. That prevents DPack setup application from detecting the correct/required .NET version. Until this problem is resolved I’d suggest downloading DPack from within VS 2012 using Tools|Extensions and Updates. The only downside of that is that you won’t get the custom keyboard bindings that come with a standalone DPack setup application.
VS 2013 support remains to be a moving target. RC has been recently released and compatible DPack beta version should follow in a few weeks. As a reminder, DPack for VS 2010 development will be retired once DPack for VS 2013 RTM compatible version is out.