Hey Celt, I also have 1.5 like you and this method mentioned above wouldn't work for me either, so what i did was move all the factions in the nonplayable section(Pontus, Numidia, etc.) into the unlockable section. I then beat a short campaign as the Brutii and there all the factions were, ready for me to start a campaign with them. So you should definitely give this a try mate.