Search in backoffice for title 'toto' is converted to
title like '%toto%'
Search in backoffice for title 'toto,titi' is converted to
title like '%toto%' or title like '%titi%'
Search in backoffice for title 'toto,titi' and lastmodifier before 2/2/13 is converted to
title like '%toto%' or title like '%titi%' and lastmodified < '2013-02-02'
As you can see, there are missing parenthesis, should be
(title like '%toto%' or title like '%titi%') and lastmodified < '2013-02-02'