Grabs related links from Google Blog Search, inserts a link to them into your post and gives them a pingback.
External Related Posts uses either your post's tags, categories, or title to search for related blogs. Try changing your tags, categories or title -- this will also change the results you get.
Not every post will return results. There are a few potential reasons for this:
External Related Posts needs to fetch and process Google search results in order to do its job.
The script is either running out of memory or executing for too long.
This can be remedied in two ways:
memory_limitin your php.ini, or
Set "Chance of Running" to 0% until you want to use it again.
Delete the previously added links (including the title added by External Related Posts) from the post.