I suspect the testers turn up and say "We want to test a, b & c and the paperwork says they should be here but they aren't". However we know where they are and go and get them or they've just forgotten to say they're not going to be where they should be. The latter is a common problem apparently but players are a bit thick and don't always realise they're supposed to keep the club informed of their whereabouts at specified times. The other problem is that it's seen as a club issue, rather than an individual one, even if the club has done as much as they can to ensure everything's in order.