Omeka has encountered an error

Zend_Http_Client_Adapter_Exception

Unable to Connect to tcp://bush.unishk.edu.al:80. Error #0: php_network_getaddresses: getaddrinfo failed: Name or service not known

#0 /var/www/html/adsh/application/libraries/Zend/Http/Client.php(1059): Zend_Http_Client_Adapter_Socket->connect('bush.unishk.edu...', 80, false)
#1 /var/www/html/adsh/application/libraries/Zend/Feed/Reader.php(292): Zend_Http_Client->request('GET')
#2 /var/www/html/adsh/themes/bush/custom.php(66): Zend_Feed_Reader::import('http://bush.uni...')
#3 /var/www/html/adsh/themes/bush/index.php(33): display_feed('http://bush.uni...')
#4 /var/www/html/adsh/application/libraries/Omeka/View.php(113): include('/var/www/html/a...')
#5 /var/www/html/adsh/application/libraries/Zend/View/Abstract.php(888): Omeka_View->_run('/var/www/html/a...')
#6 /var/www/html/adsh/application/libraries/Zend/Controller/Action/Helper/ViewRenderer.php(900): Zend_View_Abstract->render('index.php')
#7 /var/www/html/adsh/application/controllers/IndexController.php(24): Zend_Controller_Action_Helper_ViewRenderer->renderScript('index.php')
#8 /var/www/html/adsh/application/libraries/Zend/Controller/Action.php(516): IndexController->indexAction()
#9 /var/www/html/adsh/application/libraries/Zend/Controller/Dispatcher/Standard.php(295): Zend_Controller_Action->dispatch('indexAction')
#10 /var/www/html/adsh/application/libraries/Zend/Controller/Front.php(954): Zend_Controller_Dispatcher_Standard->dispatch(Object(Zend_Controller_Request_Http), Object(Zend_Controller_Response_Http))
#11 /var/www/html/adsh/application/libraries/Zend/Application/Bootstrap/Bootstrap.php(97): Zend_Controller_Front->dispatch()
#12 /var/www/html/adsh/application/libraries/Zend/Application.php(366): Zend_Application_Bootstrap_Bootstrap->run()
#13 /var/www/html/adsh/application/libraries/Omeka/Core.php(165): Zend_Application->run()
#14 /var/www/html/adsh/index.php(29): Omeka_Core->run()
#15 {main}