if es false marking could just be keen Did you just try the dog the once in empty earth, I bought a black dog years ago that false marked the first earth I tried him in, I then dug him in the next earth that was holding, this went on for a few more times he'd false mark but if there was 1 in we would get a dig, ths went on for a few weeks then he stopped false marking
mate we checked loads of earth's took him on test as a no holes bard 100% real deal digging dog held him for 2 weeks coz he was in poor condition had one last week with him on me own took him this week and like I say false marks