Warning in issuupress.php on line 167

Hi, sice some day i’ve this error:

Warning: Invalid argument supplied for foreach() in /web/htdocs/www.blobmagazine.it/home/wp/wp-content/plugins/issuupress/issuupress.php on line 167

Can you help me, please?
Thx

Url: http://www.blobmagazine.it/wp/sfoglia-il-pdf/
Wordpress ver. 3.5.1
Corrent theme: Project AR2

http://wordpress.org/extend/plugins/issuupress/