Dal manuale di MySQL (http://dev.mysql.com/doc/refman/5.0/...-language.html):

By default, the search is performed in case-insensitive fashion. However, you can perform a case-sensitive full-text search by using a binary collation for the indexed columns. For example, a column that uses the latin1 character set of can be assigned a collation of latin1_bin to make it case sensitive for full-text searches.
Hai provato ad effettuare le query tramite console e su un set di dati di prova per verificarne il comportamento?