Why command "edge" do not working with argument "canny"??

bw1 = edge(I,'canny');

I need to use canny edge but it is not working as "sobel" and "prewitt" in previous command!!

[Walter Roberson]

It works for me in R2016a. Which version are you using?

[Abdelrahiem Hashem]

R2013a, but when I explored help for "canny" I found information.