The MM_ERROR would imply either a problem with your recordset or your connection. Can you open the recoreset and does it test properly?
Getting an exact word match and/or having it automatically look for the plural is difficult and would require hand coding. I can help with that in a premium support ticket.
Another option might be to use the Google Search in our Free tools. It has advantages and disadvantages, but google has a much more complex search algorithm that accounts for full and partial word searches and orders the results by relevance. As long as your details pages are indexed your products would return in the search.