Nimbus theme problem

I’m using a wordpress theme called Nimbus (here is the demo), but after I’ve installed it, I do not manage to LOAD DEMO CONTENT (it would help me load some example content, such as tabs etc…).

It gives me the following error:

Warning: copy() [function.copy]: php_network_getaddresses: getaddrinfo failed: Name or service not known in /home2/politica/public_html/wp-content/themes/democrat/nimbus/demo/load_demo.php on line 23

Warning: copy(https://www.politica-ticinese.ch/wp-content/themes/democrat/nimbus//demo/images/demo_image.jpg) [function.copy]: failed to open stream: php_network_getaddresses: getaddrinfo failed: Name or service not known in /home2/politica/public_html/wp-content/themes/democrat/nimbus/demo/load_demo.php on line 23
Unable to copy https://www.politica-ticinese.ch/wp-content/themes/democrat/nimbus//demo/images/demo_image.jpg to /home2/politica/public_html/wp-content/uploads/2013/10/demo_image.jpg.