Problems with Plugins (no replies)

HI,

1. I get this error message
Class 'Piwik_Plugin' not found in /home/trinkgu/public_html/xxx.de/piwik/plugins/SecurityInfo/SecurityInfo.php on line 17

2. Whenever I download a plugin, I cannot unpack it, it unpacks an empty folder (Win Zip7)

any idea?

Thx

Dan