So you see even in the 21st. Century of mind boggling technology in electronics those impish bugs are busy little guys and equipment can say 'no' when its truly 'yes'. That can happen with all monitoring equipment really, it might register, oh! lets say a transponder for example, but then again it might not. Always that element of doubt with technology isn't there.
Anyway all is now well again, Arnold is there - California lost and found.