Realize that you bought yourself a radar/laser detector, not a 'POLICE' detector.bentol888 said:
The cops you passed where your detector did not go off means they did not have their radar guns on. Also realize that when it comes to laser, when your detector goes off, the majority of the time it means you've been nailed if it's not falsing, which does happen with a lot of rear brakelights and occassionally from the neon signs in storefronts.