More details, please, Stealthed.
Remember, all of these speed-detection countermeasures - no matter what you get or how much you pay - are, in the end, only tools.
They can only function within their parameters, and the enforcers can set their traps so as to make the tasks of the countermeasure device near impossible.
There's a local enforcer, a fellow car-nut who is on my local Subaru Forum, who makes a hobby out of ticketing one particularly stupid speeder in his area.
Guess what this particular speeder uses?
And guess how many times just this one enforcer has cited him?
Please let us know what happened, in more detail - maybe we can find some way of helping you improve your odds, by dissecting the encounter.