I wouldn't worry about it. Us hubbers don't always get comments on all our hubs. If you have written a hub from your heart then that is great in and of itself. Personally, I am more interested by how many page views I'm getting than how many comments, although of course it is always nice to get comments. Look at comments as 'the icing on the cake' - it's a nice extra, but nothing to be concerned about if it doesn't happen.