Hi Rod, only trapping during the day may be one of your problems as they may not be finding the traps I would normally expect to have traps out for at least 48 hours with the door locked open or the trap top down to get them used to it then turn it over and set it checking at least twice a day if this is not feasible then I would suggest speaking to a local pest management team or looking at Karnia traps as these don't need checking as often as they are break neck traps and there is no animal welfare issue.
hope this is of help
ttfn Kester