Caesar in Gaul DLC

[easytarget]

Anyone had any luck forming confederations? I've tried repeatedly and gotten no takers, made no difference if we were on friendly terms, not friendly terms, I'm about to wipe you off the planet, we're equal militarily, not equal militarily, etc etc etc. At this point I've tried under just about every possible circumstances you can cook up, nothing.

Is this a last stage then beyond military alliance and therefore just about so hard to attain there's no point? Yet I see these being formed by the AI frequently.

W/O the ability to get some diplomacy cooperation I've fallen back to plan B, which all of these barbarians in my midst appear to understand well enough, which is a spear through the eye socket.