Invalid controller specified (robots.txt)

#0 /mnt/store/data/vanluk/vanluk.co.nz/library/Zend/Controller/Front.php(936): Zend_Controller_Dispatcher_Standard->dispatch(Object(Zend_Controller_Request_Http), Object(Zend_Controller_Response_Http))
#1 /mnt/store/data/vanluk/vanluk.co.nz/index.php(53): Zend_Controller_Front->dispatch()
#2 {main}