I'm not able to purchase the in-app expansion.

I've figured out what was causing the problem.

I have the Onavo Extend service installed, which compresses downloaded cellular data to reduce data plan usage. I understand this is achieved by routing downstream data to Onavo's servers, which compress that data and sends the result via a VPN connection to the iPhone. It works very transparently, so I tend to forget it is there. On a hunch, I disabled its VPN connection in the iPhone settings and retried my failed in-app purchases (after my previous report, I had the same problem in Car Finder), and the purchases executed just fine.

Thanks.

First of all, I've only had my iPhone 5 (my first smart phone) since late November, so I'm no expert.

Having said that, first, be sure you also turn off the On Demand option for the VPN. When I was working on this, I found that just turning off the VPN in the main iPhone Settings wasn't sufficient because it would turn itself back on (in fact, at this moment, every time I turn off the VPN, it turns itself right back on without letting me even get to the On Demand setting).

But after I had resolve my problem, I receive a response from Onavo (support@onavo.com) giving their recommended workaround for failing in-app purchases caused by their VPN. Here are their steps to follow within the Onavo Extend app:

"Go to the app settings (top right)

Set 'Service Status' to Off

Try using the app."

If this doesn't work for you, and you are using Onavo Extend, I'd suggest contacting Onavo support at http://www.onavo.com or support@onavo.com.