[TYPO3-mvc] How to call an extbase controller within scheduler task

[Sören Kracker]

Hi,
I need to call a controller of my extbase extension using a task of 
TYPO3 scheduler.
I always get following error (manually called in backend with admin user):
The default controller can not be determined. Please check for 
Tx_Extbase_Utility_Extension::configurePlugin() in your ext_localconf.php.

My configurePlugin:

Tx_Extbase_Utility_Extension::configurePlugin(
     $_EXTKEY,
     'Myplugin',
     array(
         'Mycontroller' => 'list, import, show, new, create, edit, 
update, delete',
     ),
     // non-cacheable actions
     array(
         'Mycontroller' => 'create, update, delete, import',
     )
);


Here's the scheduler class:

class Tx_Myext_Utility_Scheduler extends tx_scheduler_Task {
     public function execute() {
         try {
             t3lib_div::devlog('--- working ---', 'myext', 0);
             $configuration = array(
                 'extensionName' => 'Myext',
                 'pluginName' => 'Myplugin',
                 'controller' => 'Mycontroller',
                 'action' => 'import',
                 'switchableControllerActions' => array(
                     'Mycontroller' => array(
                         'actions' => 'import'
                     )
                 )
             );
             $bootstrap = 
t3lib_div::makeInstance('Tx_Extbase_Core_Bootstrap');
             $bootstrap->run('', $configuration);
             return TRUE;
         }
         catch(Exception $e) {
             t3lib_div::devlog('--- error ---'.$e->getMessage(), 
'myext', 0);
             return FALSE;
         }
     }
}

I'm not sure if my bootstrap-call is correct. Maybe somebody got a 
working example how to do this?!

Greetings,

Sören