I have been placing blogposts in a couple external blogs about my website for the last years. But today I noticed that many of the posts in lots of blogs have no PR. It says 'unranked'. I have checked today, and more than 10 blogs (pr4+, aged domains...) have absolutely no PR.. I checked the archives, for older posts, and no PR.. Is it worth to place posts in external blogs ? Am I wrong ?
sometimes it can be very beneficial for your site...But largely depends on the PR of the blog or site.
In that case you can move to some other blogs to submit your articles. Submit your blogs at high PR sites with good traffic.