Alexander,  seems like your language ( Russian) has missing values. Go to admin panel> languages> available languages>click on the number under "Missing keys" >and translate missing values.

When I tried to add my own keys for the Forum and I got this error: 

OW Debug - ExceptionMessage:SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'LIMIT 0, 1' at line 1File:/home3/deaglesh/public_html/ow_core/database.phpLine:305Trace:#0 /home3/deaglesh/public_html/ow_core/database.php(305): PDOStatement->execute() #1 /home3/deaglesh/public_html/ow_core/database.php(339): OW_Database->execute('SELECT * FROM o...', NULL) #2 /home3/deaglesh/public_html/ow_core/base_dao.php(114): OW_Database->queryForObject('SELECT * FROM o...', 'BOL_LanguageVal...') #3 /home3/deaglesh/public_html/ow_system_plugins/base/bol/language_value_dao.php(199): OW_BaseDao->findObjectByExample(Object(OW_Example)) #4 /home3/deaglesh/public_html/ow_system_plugins/base/bol/language_service.php(223): BOL_LanguageValueDao->findValue(2, NULL) #5 /home3/deaglesh/public_html/ow_system_plugins/admin/controllers/languages.php(347): BOL_LanguageService->getValue(2, 'admin', 'questions_quest...') #6 /home3/deaglesh/public_html/ow_system_plugins/admin/controllers/languages.php(267): ADMIN_CTRL_Languages->getReordered(Array, 2) #7 [internal function]: ADMIN_CTRL_Languages->index(Array) #8 /home3/deaglesh/public_html/ow_core/request_handler.php(266): ReflectionMethod->invokeArgs(Object(ADMIN_CTRL_Languages), Array) #9 /home3/deaglesh/public_html/ow_core/application.php(300): OW_RequestHandler->dispatch() #10 /home3/deaglesh/public_html/index.php(65): OW_Application->handleRequest() #11 {main}Type:PDOException