We had issues with our older two. Our youngest trained late, but we sent her to a different day care than her older sisters - one that did not insist on being trained to move up to the preschool class - so we had a more relaxed approach with her (and she trained quickly when she did train).
Eldest refused to use the potty for bowel movements and rewards did not work. We solved that one by telling her she could not watch any kid shows or videos until she was trained. We did not cut off her TV viewing (my kids watch a lot of TV). We just told her she could only watch CNN or CNBC. She trained quickly after that.
Middle kid just did not care about the potty at all. She would hold it in all day at day care, then could hold it no more (at about 3.5 years). She would wet herself, with pants and socks soaked. We'd ask if she wet herself, she would reply "No" and walk away as if nothing had happened - she did not care. Promises of rewards or threats (such as withholding TV) did not help.
She finally came around and stopped wetting herself, but would not cooperate with bowel movements. Right before she turned four, and a week before she was going to her older sister's school where potty training was expected, we were on vacation. I told her they would kick her out of school and leave her sitting on the curb if she didn't use the potty. She finally did use it. Maybe it was the threat, but DH swears it was traveling to another country (we were in Canada), so not sure what clicked.
He will probably come around soon. Could be a control thing or a kid who just doesn't care. Middle kid (18 years old) still says she aspires to make a lot of money, retire early and sit on the couch watching TV,with mini-fridge beside the couch - and she'll wear a diaper so she doesn't need to get up.
