命令行不能自动加载模型

我试图用Yii在命令行上运行命令。我的方法需要一个模型，但是当我运行命令时，Yii说模型不存在，好像它没有自动加载它。我的课相当简短:

class ImportCommand extends CConsoleCommand {
    public function actionIndex() {
    }
    public function actionImport() {
        ini_set("display_errors", 1);
        set_time_limit(0);
        $cores = Core::model() -> findAll(array('limit' => 300000));
        foreach($cores as $core) {
            $core -> syncLocation();
        }

    }
}

错误信息如下所示:

./yiic import import
PHP Warning:  PHP Startup: Unable to load dynamic library '/opt/local/lib/php/extensions/no-debug-non-zts-20090626/php_xsl.dll' - dlopen(/opt/local/lib/php/extensions/no-debug-non-zts-20090626/php_xsl.dll, 9): image not found in Unknown on line 0
PHP Error[2]: include(Core.php): failed to open stream: No such file or directory
    in file /Users/dixond/Sites/nevada/yii/framework/YiiBase.php at line 421
#0 /Users/dixond/Sites/nevada/yii/framework/YiiBase.php(421): autoload()
#1 unknown(0): autoload()
#2 /Users/dixond/Sites/nevada/pub/webservice/protected/commands/ImportCommand.php(15): spl_autoload_call()
#3 unknown(0): ImportCommand->actionImport()
#4 /Users/dixond/Sites/nevada/yii/framework/console/CConsoleCommand.php(172): ReflectionMethod->invokeArgs()
#5 /Users/dixond/Sites/nevada/yii/framework/console/CConsoleCommandRunner.php(67): ImportCommand->run()
#6 /Users/dixond/Sites/nevada/yii/framework/console/CConsoleApplication.php(91): CConsoleCommandRunner->run()
#7 /Users/dixond/Sites/nevada/yii/framework/base/CApplication.php(169): CConsoleApplication->processRequest()
#8 /Users/dixond/Sites/nevada/yii/framework/yiic.php(33): CConsoleApplication->run()
#9 /Users/dixond/Sites/nevada/pub/webservice/protected/yiic.php(7): require_once()
#10 /Users/dixond/Sites/nevada/pub/webservice/protected/yiic(4): require_once()

要让Yii自动加载模型，我需要做什么特别的事情吗?