Unrecognized DAO ConferenceStatisticsDAO

Stack Trace:

File: /var/www/org.ecoinformatics.conference/ocs-2.0.0-1/classes/db/DAORegistry.inc.php line 59
Function: daoregistry::getqualifieddaoname("ConferenceStatisticsDAO")

File: /var/www/org.ecoinformatics.conference/ocs-2.0.0-1/pages/about/AboutHandler.inc.php line 431
Function: daoregistry::getdao("ConferenceStatisticsDAO")

File: (unknown) line (unknown)
Function: abouthandler::statistics(Array(0))

File: /var/www/org.ecoinformatics.conference/ocs-2.0.0-1/index.php line 46
Function: call_user_func(Array(2), Array(0))

File: /var/www/org.ecoinformatics.conference/ocs-2.0.0-1/index.php line 57
Function: handlerequest()