I agree that letting them lead is key. With the little guy I have in care who is trained at home, but not with me, I pushed him too much in the beginning as I was feeling pressured by his parents. It was disastrous! He ended up holding it for an entire day and writhing in pain! At that point I told parents we had to stop training at my house as I didn't want him to be in pain and it was obviously not working at all. Now it has been months and there is no progress at all although he is doing well at home. Now all I can do is wait and hope that sooner or later he feels comfortable trying at my house.