I also have found that general searches are more effective if you use the advanced search "search as a phrase" option. For whatever reason, it seems to do a better job than the others. Also - be sure to adjust the date range. It is set up a bit akwardly so that when I search, I sometimes find I have not set my time parameters correctly. Finally, if it is a topic with a lot of posts, be sure to adjust the total number of posts you want to retrieve. I think the default is 50.