AP votes get cancelled if they can no longer take place, such as the case of "stop trading with the infidels" (one can only call a stop-trade on non-AP members, and once the AP religion spreads to one of their cities they're considered a partial member even if they're running a different religion). If you ever need to deny a "stop the fighting between our brothers of the faith" resolution but can't afford to defy it, by the way, sign a ceasefire the turn the vote comes up, next turn the resolution will be cancelled (since there's no war to put an end to) and you'll be able to re-DoW since a ceasefire doesn't impose a peace treaty. You'll lose your current war success, get another round of diplo penalties for DoWing and you might end up with your army displaced, but you can resume the war without having to wait out a peace treaty or eating the penalty for defying a resolution.