I have an Verizon iPhone 4 running iOS 4.2.6.

I jailbroke it yesterday using the latest greenpois0n build, installed Cydia, blah blah blah.

I downloaded and installed the latest Navigon MobileNavigator (US + Canada). Now I'm trying to install Navigon's Traffic package. This is an in-app purchase so I assume there's no way to crack it, so I'm fine with purchasing (since it's a one-time fee). However, when I run the app, click "Extras", I get the following message:

"No additional products available."

Is this because my phone is jailbroken, I'm running a cracked version of the app, or is it Verizon related?

Any help would be appreciated.