In app subscription purchase over 3G says wifi must be available?

I'm working on an iOS app that uses in app subscriptions and one of the testers has reported that when trying to buy a subscription over 3G they get a message that reads:

"Wifi Required. This i开发者_JAVA技巧tem can only be downloaded over a wifi connection."

Anyone seen this before? It makes no sense that users can't subscribe over 3G. It's just a receipt that gets returned, not megabytes of data.

If your testers use iOS 5 beta they can try Settings > Store > Use Cellular Data [ON] and plz remember that iOS 5 beta still under NDA :)