OK then, that MUST be it. The OS 7.1 is needed to use this theme. I'm sorry, when you said Got it, I somehow thought it started working for you! :(
I would say upgrading is the thing to do but if you are not comfortable, then of course, don't do it. I personally upgrade to every leak and OS that comes down the pike, but some don't care to do that. Sorry.
Wish I could help you to get this to work.:(