Hey Col, not trying to be a smart-arse, but did you remove the plastic off the batteries??
Bought one for sh*ts and giggles, just took it out the back paddock and checked out the silhouette range. All checked out, distances were +/- 2m at 200, 300, 385 and 500m, sighting on the silhouettes themselves.. Got good results at 600, 700 and 800 yards. Unable to get any readings at 900 and 1000 but my splash-plate is only about 4ft high by 2ft wide.
I'll try it again some other time with a bigger target to aim it at, a vehicle perhaps.
Was actually after a couple of cameras to put at the front and back gates to the farm, sick of "unwanted" visitors coming in through the neighbors. No luck, all gone at the 3 stores we went to.