well, i forgot say i have native female/women inside milker, who was pregnant and was giving succes. birth. and near it is npc who is worker for livestock with food+water but still not milk.make sure they have given birth successfully once, are fed and just leave them inside it for awhile, it takes some time for the milk to be milked, you can also just sleep through the day to skip some of the waiting. So far workers on it dont seem to do anything with it