Over the years I've owned these dogs I've never kept them out on chain in a "yard" set up, not that I disagree with it, just not for me I prefer indoors because I don't have many....now I sat in a beautiful "daze" the other day & tried to figure out why the hell all of my dogs would work a mill from a puppy on up, and wouldn't work a Jenny for me if I roasted a pig in front of em! THEN IT HIT ME! I walk my dogs early on in life on up through adulthood on lead & collar/harness which is a similar feeling to my dog when hooked up to the mill. On the flip side the only people I knew personally that could get theirs to work the Jenny had the dogs on chain set ups which depending how the the doghouse is positioned makes the dog trott in a circle like it would on a Jenny so I guess that is why when they get hooked up to one they just go! Lol may sound a lil corny but damn it took me almost 15 yrs & and an Amsterdam cigar to figure it out!