I had a cobra detector ( 3 band, K,Ka,X, plus laser )...but it did not work on the motorway (or anywhere for that matter)....
I was later told that detectors work according to regions i.e any detector bought from the middle-east should work in pakistan, but would not work in the U.S. and vice versa....
Different regions use different frequencies for the same band. Please correct me if im wrong.