Article Backlinks Not Working?

I am fairly new to Article Marketing (on and off for just under two months) and have been bookmarking, submitting my articles to article directories and putting my links on web 2.0 sites each time I wrote a new one.

Just been checking all of my articles using Market Samurai, and it only shows 1 or 2 backlinks for only a couple of articles?

Any reason why this could be?

Thanks in advance!