You might just need more traffic. If you take a look at this story on my blog about sleeping on long flights (http://blog.jgc.org/2010/06/how-to-sleep-on-long-haul-flight...) you'll see that it has 14 comments. A quick look in Google Analytics says that it had 22,994 page views. So one comment per 1,600 page views.
I get about 1 comment and 1100 page views a day, which is a similar ratio. Thanks to an Intense Debate/Feedburner bug (FB adds ?=... to the end of the article link in the RSS and ID treats it as a different page for comments) I've noticed I actually get a lot of my comments from my 1600ish subscribers though.
Another blog post, about messing around with an Ikea train set (http://www.jgc.org/blog/2010/01/more-fun-with-toys-ikea-lill...) received 26 comments and has 56,373 pages views. So one comment per 2,200 page views.
One last example about squaring numbers in your head (http://www.jgc.org/blog/2010/03/squaring-two-digit-numbers-i...) has 15 comments and 21,380 page views. One comment every 1,400 page views.
So, more traffic helps. What's the URL of your blog?