When you say that you have limited the site to 42 pages do you mean that you made a copy of the site that only had a total of 42 pages?
If this is the case and you were able to get successful results with the other site that had 59 pages it would indicate that it is not the size of the site that is a problem. Is there a link you can post to the smaller version of the site, or if you are not able to post a link can you post a copy of the smaller site in a zip archive?
If the size is not the problem it is probably related the structure of the site and possibly the names of the pages in the site. In order to determine this I will need to do some testing.
