The game in this case is Minigore, and this happened with Pocket God too. When I click Online, a message on the bottom of the screen says "error: can not log on to openfeint" I havnt even made an account yet! When I first got the game I clicked Online and clicked cancel because it was taking too long. now this happens....
I think it's because anyone who posted more than 50 times on the upcoming Minigore thread was banned from the use of OpenFeint. Could this apply to you? Maybe that's what it is.