Wrong Charset

Hallo Forum!

Nach Installation und Aufruf von Piwik bekomme ich folgende Fehlermeldung:

Könnt ihr mir weiterhelfen?

Notice: iconv_strlen() [function.iconv-strlen]: Wrong charset, conversion from UTF-8' toUCS-4LE’ is not allowed in /home/sites/site25/web/piwik/libs/Zend/Validate/Hostname.php on line 619

Backtrace -->
#0 Piwik_ErrorHandler(…) called at [:]#1 iconv_strlen(…) called at [/home/sites/site25/web/piwik/libs/Zend/Validate/Hostname.php:619]#2 Zend_Validate_Hostname->isValid(…) called at [/home/sites/site25/web/piwik/libs/Zend/Uri/Http.php:445]#3 Zend_Uri_Http->validateHost(…) called at [/home/sites/site25/web/piwik/libs/Zend/Uri/Http.php:277]#4 Zend_Uri_Http->valid(…) called at [/home/sites/site25/web/piwik/libs/Zend/Uri/Http.php:154]#5 Zend_Uri_Http->__construct(…) called at [/home/sites/site25/web/piwik/libs/Zend/Uri.php:145]#6 Zend_Uri::factory(…) called at [/home/sites/site25/web/piwik/libs/Zend/Http/Client.php:305]#7 Zend_Http_Client->setUri(…) called at [/home/sites/site25/web/piwik/libs/Zend/Feed.php:170]#8 Zend_Feed::import(…) called at [/home/sites/site25/web/piwik/plugins/ExampleRssWidget/ExampleRssWidget.php:103]#9 Piwik_ExampleRssWidget_Rss->get(…) called at [/home/sites/site25/web/piwik/plugins/ExampleRssWidget/ExampleRssWidget.php:62]#10 Piwik_ExampleRssWidget_Controller->rssPiwik(…) called at [:]#11 call_user_func_array(…) called at [/home/sites/site25/web/piwik/core/FrontController.php:138]#12 Piwik_FrontController->dispatch(…) called at [/home/sites/site25/web/piwik/index.php:53]