see what happens when they go in to their home in the evening (they have a small cubicle or stall or something,no?) ; some does prefer privacy and will let their kds nurse once in side. also, could be her milk just came in all at once *third day or so, no?) and she is too full or painful so you can hold her, feed her her grain, or her snacks or tidbits or some tasty hay, and see if she iwll allow the kid to nurse. check her udder, u might have to milk her a bit to release some pressure: tie her or have someone hold her, with some nice yummies to munch on, and massage her udder with your warm hand, slowly, all around the udder, then grasp the teat and milk her a bit, then see if the kid will nurse. remember, mothering is a learned behavior with goats (as well as instinctive) so new mothers are just that: NEW MOTHERS. so sometimes they need a mother's helper... sometimes does want to eat their meal in peace and quiet and a kid coming to nurse all the time bugs them... if teh kdi isnt bawling its head off, or weak and cool, but seems perfectly happy and bouncy, and not really hungry, then leave them alone. if the kid seems seriously hungry and is crying and upset , then u will heave to get the doe into a routine of letting the kid nurse. i would keep her locked up with the kid a few more days , i usually make new mothers 'bond' with their kids for a week before they go outside. experienced mothers , well, u learn their personalities and what works for them...
the best thing to do is to sit back and watch, unnoticed, for a long period of time thruout the day, before u get worried. sometimes its like with people who say their kids dont eat, but the child is snacking all day long in small amounts. kids dont nurse long periods of time, like a human baby, they take a few long drinks, play, then come for more/
also check that the doe doesnt have an infection, and the kid is nursing from both sides; it could be that it keeps going to the easier side which is emptied, and it bugs the doe and the other side is too full and hurts her....