Night Ranger was a little popular back in 1983-1984. The problem is, that unless you actually lived in the 80s (I was 18 at the time) you probably wouldn't have heard of them. They basically had one or two songs that were popular for a few months.
Because there are 80s bands that are far more important, or popular, than Night Ranger (such as U2 for example), someone who didn't live in the 80s would probably have never heard of them. I would say that Night Ranger was a little more popular than say, Devo, but not much more.