D.M.
My Ped told me that night time training isn't so much "training" as readiness by their bodies. Some kids take until 5 or 6 for their bodies to recognize the need to go and get up and go. If this response isn't there physiologically (spelling???) then you can't train them and you have to wait until they are ready.... Having said that if they are dry sometimes, they are getting there. After they are dry more often, then you can try it... also if they wake at night, take them directly to the bathroom to get them in the habit. Don't push it however, because they likely just can't control it if they are wet that often!