Watchdog Statistics did not work since Update to 8.1

[dawart]

Hi,

since I've updated to 8.1, the Watchdog Statistics did not work anymore - in does no lo display graphs.

The Function "Server" -> "Statics" also did not work anymore. When I click on it, I get the following error:

ERROR: PleskFatalException  	
StatInfo->getActiveDomainsNumber() failed: devices number <= 0

0: /opt/psa/admin/plib/class.SystemStatisticsForm.php:145
    SystemStatisticsForm->assign(object of type StatInfo)
1: /opt/psa/admin/htdocs/server/statistics.php3:27

Anybody here knows how to fix it?