I\'ve been running my app on an iPhone 5 /iOS 6, but when I try to run it on an iPhone 4S / iOS6 I get \"The run destination iOS Device is not valid for running the scheme N
It was a bug in XCode, I closed and reopened Xcode and it started working.
I've noticed this sort of thing many many times now with Xcode with other problems, its very frustrating that the tool is so dodgy.