iDebug Exception:Call to undefined method UserApp::api_message in iCMS://iPHP/Application.php:216 on line 216

1. iCMS::API() in iCMS://public/api.php on line 12
2. iCMS::run(NULL,NULL,NULL,"api_") in iCMS://core/iCMS.php on line 103
3. Application::run("user","message",NULL,"api_") in iCMS://core/iCMS.php on line 98