The dog as become conditioned to a certain situation,its reacting to past experiences and acting accordingly,as certain Collie types are prone to do,its not lazy or jacking as some would have you believe.Change the situation to give the dog more stimulus,ferreting bunny,s,working free,daytime,having to use its senses to locate,run and catch,if lamping change your lamping style,use a filter,shorter and kicked up slips,no long slips and slips that have the bunny running towards cover.Stay off ground the dog is accustomed to,nothing will cure the dog fully now,they soon learn to work any situatio