That Riddim is Hot, top production.
As regards to an artist of his calibre & indeed everyone, promotion is everything.
Snoop Lion did heavy promotion, don't think it sold that much, but at least people knew about it.
Promotion costs more than production, check all those pop artists on yahoo & other search engines & street teams posting flyers .
Too much good reggae stays pretty much unknown because of lack of promotion.
As it's been said before, talent makes up only 10 % the other 90 % consists of other things.
Also remember the flipside, guys like Shaggy does not have to sell units, touring is his bread & butter.
Many artists don't have to sell , they still play gigs.