freeradius sql modul faild to load

Hello. I have freeradius 2.1.9 on Fedora 13. I also have mysql-server installed and freeradius-mysql package. I created database with Daloradius sql script and everything works, but when i uncomment "sql" in /raddb/sites-enabled/default file, freeradius gives error, failed to load sql modules. what can i do? please help me.