What would cause a Fuzzy Lookup to return a Null set of values from the reference table?

I'm doing a fuzzy lookup on a view of a table which does a fine job returning similarities with the occasional exception, and I can't seem to figure out what is causing the problem. Every so often, the comparison will come up with null values开发者_开发技巧 from the lookup view, even though the values exist in both the view and the original table and the columns I have selected for "exact" match have identical values in both the lookup view and the source SQL.

Any thoughts as to why it's pulling null values?

alt text http://img689.imageshack.us/img689/4846/fuzzylkp.jpg

I discovered that by changing the order of the columns, and placing the exact matches at the top of the list, the null results were returned properly.

Change your MinSimilarity threshold in the advanced settings - See this article