Yea ectomorphs do have a lot harder time putting on muscle than the other soma types. It is possible though, but you have to workout smarter and not harder. Certain ectomorphs have a tendency to get hurt easier lifting heavy weights, I think this is due mainly to the smaller bone structure compared to the other soma types. But if you are serious in gaining muscle I recommend going to this
Hardgainer site and reading all of the free articles that are on there. And signing up for the email class too.
Alot of great information for ectomorphs...
good luck to you my friend,
~Cory