Storyboard Format Unknown [New to AppCode]

Hi all,

I'm new to AppCode, and relatively new to OS X/iOS development overall. I'm having an issue with AppCode that I have no idea how to start tackling, and no amount of googling is revealing anyone else with the same issue, which surprised me. I've created a shiny new project through AppCode, with the default settings, and when I open the Main.storyboard file I'm presented with the error message: Unknown Storyboard format; I've added a screencap of the error, so that you can see exactly what I mean.

Hoping someone will know what might be the issue here, beacuse I'm completely stumped.

I'm working on a MacBook Pro (Retina, 13-inch, Late 2013), 8GB RAM, on Yosemite. If I need to add more information, let me know.

Thanks,

Rob