were you able to read the data properly and reproduce Andres code? R is always tricky at start, but reading datasets can be complex as there is some kind of "mother function" with a lot of wrappers for certain specifications. If any other doubt on these topic, or any one, please don't forget to include the code and try to make a reproducible example. The more information you provide (and the better formatted), the easier for people to help you.
Good luck