That's why I suggested trying a few times, each time stand a little closer to the pen. I figure if you try herding them 70 feet it won't happen. I can herd mine almost 200 feet from the pond to their pen however it only happens every once in a while, they normally come up to their pen as soon...
Can you carry some treats out (frozen peas perhaps) a few days in a row while calling "duck duck duck" and see if they become interested? If it works then continue to do it working your way closer to the pen you want them in until you can corral or herd them in there.
Good luck!
Michelle