The syntax you've given is : neostripcolor({start pixel},{end pixel},{R},{G},B}) : which is how I'd expect it to work.
e.g. neostripcolor(2,4,{R},{G},B}) would light pixels 2, 3 and 4.
What i'm finding is I have to add 1 to the end pixel value to get the expected effect, so to light pixels so to light 2, 3 and 4 I need to use : neostripcolor(2,5,{R},{G},B})
Lighting pixel 1 on its own would be start = 1 and end = 2 rather than the more logical start = 1 end = 1.