Where's Ziplock

My girls don't listen to me but Zip does. He will sit for me almost everytime that I ask him to. If you look at this video, you'll see that Jessie and Rozlin don't. He is a fun dog who likes to run in the backyard. This morning he got Rozlin running and they didn't stop for 10 minutes. After that they were down for 1/2 the day.