You might have to go in every few hours, pin the ewe to the side of the pen, and hold the lamb to the teat. It sometimes takes a few days for the ewe to accept her lambs, keep them in a pen next to her, so she can smell them but not hurt them. (but better than bottle feeding for a few weeks...) Also for the first couple of nights tube the lamb with milk/colostrum from the ewe, or goatsmilk if you have it, saves you from getting up at 2am for a feed... about 150ml at 10.30 should last the night, then start again at 6am latest in the morning.