Issues Fixed in 9012
SD-56926 : After upgrading to 9011, Some of the Dashboard charts under Helpdesk tab shows Plugin is missing / Install Missing plugin. This issue is fixed.
Please refer to the below link for the steps to install the patch.
http://www.manageengine.com/products/service-desk/service-packs.html#sp
Regards,
Edwin Vasantha Kumar
ServiceDesk Plus Team