create root locus in octave

MIT has make a clear tutorial of this topic.

http://web.mit.edu/6.302/www/compare/report.html

However, it doesn't work in my machine. 
I use the following codes to create a root lucos and it works!

s = tf ('s');
L = 3e4 * (0.05*s + 1)^2 / ((s+1)^3 * (0.01*s + 1));
rlocus(L);

It seems that matlab perform much better ;-P